(AFP) - Jenson Button made a promising, if not perfect, return to Formula One on Thursday (May 25) when he wound up 12th at the end of Thursday practice for the Monaco Grand Prix.

Taking over two-time champion Fernando Alonso's McLaren Honda for the weekend, while the Spaniard competes at the Indianapolis 500, Button produced a typically smooth performance, but admitted he had struggled with the increased pace and power of the new generation of machines introduced this year.

"I struggled with the extra grip and it was difficult to find my feet," said Button.

"You have to brake so much later than I am used to here in Monaco and you carry so much more speed.

"I'm braking in places where I have never braked before at Monaco and the grip levels were the same for years - and now it is different.

"It's got a lot more grip than I'm used to - it was so much faster in FP2. I have to find that extra bit of confidence but it is difficult because you think you'll lock up under braking that late.

"For me, the objective is to keep having fun and to prove myself. Since the Abu Dhabi Grand Prix last November, I drove a rally-cross car, in January, but that's all I've done since then - in seven months.

"I thought it might feel weird, but it doesn't, which is nice for me and I think a lot of my performance will come from me figuring out the braking and gaining my confidence."