Their harmonization is pretty good... I don't get why people are bashing Krystal.. This song requires smooth and soft voices

Chen harmonises very, very well with krystal. He's also kind enough to lower his tone so it would match krystal's. But still, krystal's voice matches this soothing song. So it's a good thing that chen did that. Don't compare their voices with other's. They've already proven themselves worthy of this song with that kind of singing. It's simply beautiful. So please just enjoy ^_^

Krystal can sound so much like Jessica sometimes. I love this song, it's really mellow and easy going, I love it.

the tune is sweet. krystal voices is sweet. chen voices is sweet i literally died on sweet x_x

Krystal fits this song! I love her voice too~ Crystal Clean, and sweet

다신 못 볼 조합이지만 슴더발 중 가장 좋아하는 노래

i like krystal's voice

This song is giving me diabetes. It's so sweet and calming. I love Chen and Krystal's voice together. Who's watching in 2016?🙋🏻

I think Chen and Krystal's voices blend better than Chen's and Luna's did. They both have really pretty voices that make any song emotional, ugh. Love it :3

She was just 19 and he was just 21 cutie pies have come a long way... Krystal waiting for your solo album❤

Chen's voice is so clear and stable, I love his singing ^^ Beautiful song, really sweet~

chens not singing really high... i love it!!! deep and hot voice chen!! beautiful!!

I can't breathe jongdae's voice is all up in me

Krystal's voice is heaven

Chen is soo good. Low note, high note, he nailed it all ✨

her voice blend well with Chen's sweet deep voice. PERFECT DUET !

둘 다 목소리 왜이렇게 예쁠까..

who's watching this in 2020? ALSO WHY IS THIS NOT ON SPOTIFY :(((

Krystal really has a sweet voice

in love with krystal's voice

I like the way that Chen sing so sweet, it really blend very well with cute voice of Krystal.. again, in few moments, I thought Jessica is singing here.. hahaha.. sweetness overwhelming..

Krystal's voice is amazing

Wow Chen is just so great

Chen gives me an indescribable feelings..

baby jung's voice has improved so much!

Everyone, STOP bashing and being mean to Krystal! Her voice is just fine. Her voice might not be as strong as Luna, but it's not bad. Please be nice, and let EVERYONE have a fair chance at singing as well! It can't always be Luna.

Krystal voice are smooth and sweet !! Krystal and chen voice blend so well ! My favs song from breath album tbh

Omg! This is my fave track in SMTown Superstar game! Never thought it was sung by Krystal and Chen

Krystal is so beautiful ajd her voice is super sweet tooo!!!!

Can we just take a moment and comment on how amazing Chen sounds?

Luna has an incredibly powerful voice but Krystal has something so naturally sweet about her singing. This song was perfect for Krystal and despite what others may say about luna being a better singer, I look forward to Krystal proving to everybody that her singing talent should be respected.

I may not be an f(x) fan, but I thought that Krystal's voice really went well with Chen's. They both worked very hard on perfecting those harmonies and I think it turned out great! :) They both sound amazing.

Fallin' in love with Krystal's voice ♥♥

I just love it when Krystal sings:)

This song is not easy to pull off and I think both Chen and Krystal sand beautifully. So people please stop complaining about how Luna should be singing instead of Krystal or saying Krystal isn't as good as some of the other members. Krystal has clearly shown she deserves to be on that stage just as much a everyone else has.

the way chen looks at krystal melt my heart..omg!their voice blend beautifully and so harmony thanks to chen kindness by lowering her voice and krystal soothing voice

I LOVE KRYSTAL

The way Chen stares at Krystal makes the song even better.

I swear, almost every idol that is a boy i see with Krystal, the chemistry is always there. How can Krystal always do that?

Chen's collaborations with anyone are great and even his own solo or station or ost or anything. Chen's voice is angelic. Lovely Chen 💜 fighting!!

Love Chen's voice and Krystal soft voice

진짜 좋긴 좋다..아직까지 듣네

Krystal did a wonderful job and so did chen. Now don't you people go negative cuz I doubt most of you could do any better. Now good day. Farewell Comment section I am scared to read because there might be hate...

Soojung my bias you're really great how amazing smooth gorgeous tender sweet voice you own!!! always love u fighting!!!!!!! best vocal forever in my heart

chen's voice is awesome!:)

Krystal voice very soft

Jung SooJung You're great, I love your soft voice, you're the right one for this project. f (Krystal)... FIGHTING....!!!

I don't know why people keep blaming things on Lee Soo Man. Why can't y'all differentiate voices? They didn't choose Krystal to sing for this song because they "liked" her more than Luna. Luna's voice is amazing, yes, but her voice is too powerful for this. Krystal has a sweeter (and sharper) voice, that's why it's more suitable for her to sing this song instead of Luna. Luna's powerhouse voice and singing techniques would take away the desired pitch for this song. Calling yourself an f(x) fan without even knowing what kind of voice your idols have is shameful. I'm standing by this, don't even think about arguing. Also, whatever happens behind the screens does not concern anybody nor the fans. Don't stir up unnecessary things. Even if they fight, it's their problem, not ours. Y'all needa calm down and take what you're given, shut up and watch what you're shown. Your bias is not "yours", they're working. As entertainers, they're already stressed more than any human being should be, so if you love your biases, stop creating extra issues for them. I hate to see how tired Krystal looks. Babygirl needs a break, even a short one would be good.

Krystal's voice is perfect for harmonizing. If u listen to f(x)'s tracks u can always hear her voice on the background. Her voice is just so delicate that it fits perfectly. Listen to goodbye summer and listen amber's part. It's amazing

They should seriously collab again and sing a ballad together!! This sounds so sweet and calming!! ❤

Krystal ♥ your voice is beautiful.

lol, so we're not going talk about how proud we are of our Chencing Machine?

It's nice to see Chen showcase his more tender and delicate singing. His vocal range is so impressive. He can either be a powerhouse, belting out the highest notes, but he could also sing gently as this song shows. His voice complimented Krystal's delicate vocals. This is a sweet and lovely song. Love it!

Beautiful duet! Love their voices together!! I'm such a huge fan of Chen's vocals but I think Krystal sung wonderfully as well:)

I love how Krystal sounds exactly like Jessica when you close your eyes...

Wae is everyone bashing Krystal?? Sure, her voice isn't as strong as Luna's, but it has a smooth, soft sound. And can't we be happy that SM decided to include f(x) for a change?? The singers are chosen and there's nothing we can do about it. Let's just enjoy the music~!!

Yea Krystal does sound like her sis when she tries to reach the high notes. But I think her tone is slightly lower than Jessica's? Both Chen and Krystal did well! Chen's starting is awesome!

It's so rare to see Kry sing like this in any form !! Blessed to see this video. She did well.

this one is better than the recording version. i love it!!

I really love this song ,and Krystals voice is soo sweet and she is so pretty

That performance was flawless. I just can't get enough of Chen's voice. And Krystal, whoa.

So in love with krystal voice. Keep singing girl, you have such a angelic voice

EXO CHEN the best voice.เสียงสุดยอดมาก เพลงก็น่ารัก

I hope Kai and Krystal can also have a collaboration like that.

I think they picked Krystal because her voice really suits the Japanese language. It sounds a lot more light and cute than Korean or Chinese. Krystal's voice fits that perfectly in my opinion.

What a beautiful, soft melody sung by amazing singers

i don't know why but I feel like everything is so sweet! their voice, the song, and the melody.. sweet and perfect! ChenStall will be my new favorite duet pair ❤️❤️❤️

Chens solo album is what i need rn

krystal your voice just melts me >< chen ah you too! both voices combine together makes perfection

OMO. I NOW SHIP THIS TWO! CHENSTAL ♡

this is an awesome duo for a sweet coupling song! =D i liked how SM planned it so well with sorting the ideal couple for each song.....awesome!

This group's combining voices are perfect too! Chen's voice can be powerful in BREATH but also soft and sweet in this song! Krystal did a good job in this song too! First love song for me in this album is Breath in Chinese ver. And second is this song, I'm not a Korean so I don't know the lyrics meaning, if I didn't check the lyrics, I really thought that Chenstal were singing a love song!

I'm falling even deeper for Jongdae if that's possible

Krystal is literally perfection.

Dear Chen my bias! I think he did the best in this song among the three... Sweet music!

krystal's voice is so sweet :x she can sing she can dance she can act she can do everything and she is so pretty :D gosh!! such a perfect girl :x

개인적으로 슴더발 앨범에서 제일 기억나는 노래 .. 진짜 세련된 노래인듯.. 지금 들어도 안촌스러움

This song is sooo sweet. Chen's voice is soo sweet and Chen and Krystal is sooo sweet T.T

Chen baby

This was actually the duet I was most excited about! I think the song & both singers are cute as hell! Of course, the other songs didn't disappoint as well, especially Chen & ZLY's 呼吸 (Breath)

Ahh this is a really sweet duet. Krystal's voice compliments Chen's so well and they have a flawless harmony together. Probably my second favorite song off of the album just because their voices fit so well together.

go krystal we are here f(x) fans to support you even my ub is sulli but f(x) is a family right so we are always here for all of you as a family

수정언니 목소리는 들어도 들어도 천국이네,, ❤️

Krystal sounds like Jessica. same sweet voice

Chen's voice... So good...

ah~! I love this duet

Krystal's voice is so soft like velvet and so beautiful. I've always loved her voice so much and I'm so happy she got a chance to showcase it!!

Krystal why so perfect

Still watch this This song is really suit with their voice Chen Krystal, they have a sweet voice Who's here again??

krystal's voice .< I LOVE IT

It's nice to hear Chen's lower register ^^ ♥ such a talented singer

Oh my goodness this was wonderful! The harmonizing was really pretty and Chen sounded so at ease with the high notes at the end of the song

They look so adorable together *_*

Chen is such a gentleman. He lowered his tone for Krystal. Aaaa I love him so much❤

love soojung!!!! people always complaining!!! just support each other members.. soojung's voice is so comfortable to listen to.. it suits the song..

Krystal awesome!!

i can't help but to ship these two, gosh they looked so adorable together haha!

Kystal's soft and sweet voice + Chen's angelic and powerful voice are so good together. Saranghae, f(exo) fighting!

I love CHEN so much

Chen look like he comfortable and having fun with the song...like it a lot chen keep it up!!