John Legend was "a little bit jealous" of Ryan Gosling on the set of 'La La Land'.

John Legend

John Legend

The 38-year-old singer plays the part of Keith in the critically acclaimed musical movie alongside Ryan's starring role as struggling jazz pianist Sebastian Wilder, and has said he was left envious by the actor's ability to play piano.

Asked during an appearance on Australian radio station Nova FM if the 36-year-old actor - who learnt to play the instrument specifically for the role - was an overachiever, the 'All of Me' hitmaker said: "The fact that he learnt as well as he did is pretty impressive for someone who didn't normally ... in fact I was a little bit jealous.

"He works so hard, I haven't seen any of his flaws yet!"

And John - who has eight-month-old daughter Luna with his wife Chrissy Teigen - previously stated he bonded with his co-star over fatherhood.

He said: "Amada [Gosling's daughter] and Luna were both born in April. We talked about it.

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

Meanwhile, John admits he is a huge fan of the 'Crazy, Stupid, Love' star and relished in the chance of working alongside him.

He added: "That made me feel a little bit more comfortable, that he was learning something new too and had that sense of ... the struggle of a new thing. I was really impressed with him playing the piano, and I thought he was doing a really good job.

"I've been a fan of his work as a film actor for such a long time, so I was excited to work with him. I was just hoping that he didn't think I brought him down too much, knowing that he's been doing this for a long time and I haven't."