EXCLUSIVE: John Legend and Emma Stone Can't Get Over Ryan Gosling's Real-Life Piano Skills in 'La La Land'

Ryan Gosling has grown accustomed to crowds of rowdy girls screaming his name, but his biggest fans might be his La La Land co-stars Emma Stone and John Legend. ET caught up with the film's cast in Los Angeles on Monday, where the stars couldn't say enough good things about Gosling.

Stone famously worked with Gosling in 2011's Crazy, Stupid, Love, in which the duo recreated the famous Dirty Dancing lift. They return to the dance floor in La La Land, so ET's Carly Steel asked Stone to describe Gosling's dance moves in three words.

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"Really super great," Stone answered.

In the upcoming musical, directed by Damien Chazelle (Whiplash), Stone plays an aspiring actress named Mia involved in a love affair with a dedicated jazz musician named Sebastian (Gosling). Set in modern day Los Angeles, the couple struggles to stay together as success mounts and the dreams they've worked so hard to cultivate threaten to come between them.

Stone and Gosling had some coaching in the dance department from Dancing With the Stars pro Artem Chigvintsev and choreographer Mandy Moore, but his two-step wasn't the only skill Gosling had to master for the project.

The actor practiced piano four hours a day for three months during pre-production to play well enough to shoot without the help of doubles, so when you see him tickling the keys on screen, that's all Gosling!

"Piano is always something I wish I had the time to learn," Gosling admitted in a featurette. "What other job is a part of your job to sit in front of a piano for three months and play? It was really one of the most fulfilling pre-production periods that I've ever had."

"I'm, like, skeptical," joked Legend, who has been playing piano since he was 4. "I'm thinking he was secretly learning since he was 4, too."

With seven GRAMMYs, a Golden Globe and an Oscar to his name, you might think that Legend had a hand in mentoring Gosling through his musical performance, but Legend said he was more focused on his own performance.

WATCH: John Legend Says He and Ryan Gosling Bonded Over Fatherhood on 'La La Land' Set

"He had a piano coach with him, so he didn't need tips from me," Legend said. "And then I was getting guitar coaching from somebody else. [Gosling] was more just telling me 'good job' on the acting stuff, so I would feel comfortable and know that I was doing OK with the acting."

Besides work, Legend and Gosling had plenty to bond over. Earlier this year, they both had daughters just days apart from each other. Legend and wife Chrissy Teigen welcomed their first child, Luna, on April 14, while Gosling and girlfriend Eva Mendes had their second child, Amada, on April 29.

"We had just announced that we were pregnant right around when we were filming the movie," Legend recalled. "He definitely kind of shared how joyous it is to be a new father and gave me something to look forward to."

Still, Luna and Amada have yet to set a play date.

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"They have not yet. She hasn't had a play date with anybody," Legend explained. "You can barely say she's had it with Andy Roddick and Brooklyn Decker's boy, Hank. But Hank is quite a bit older than her by a few months, so she hasn't really had a genuine play date with anyone her age just yet."

La La Land opens Dec. 9.