Expect the Monaco Grand Prix to be Jenson Button's final goodbye from Formula 1, after he claimed Saturday's qualifying would be his "last".

The Briton, standing in for Fernando Alonso this weekend at McLaren, had earlier not ruled taking up on a contract he has for a full-time return with the British team in 2018.

But after proving he hasn't lost any of his speed, making Q3, the tones of the 37-year-old were one of a man content to call it a day.

“To be P9, I'm very happy and I've enjoyed the weekend a lot," Button said."It's my last qualifying session, and probably one of my most enjoyable.

"I haven't missed F1, I've had such a good six months, then I get back in the car and absolutely loved it.

"I was told to have fun and enjoy it and I definitely have - not just driving the car, but the whole F1 atmosphere."

Despite his strong performance, Button admits it is hard to draw conclusions on how much potential the McLaren really has.

"I really don't know where the limit of the car is, and you can't find the limit around Monaco, you need to feel where the limit is on an open circuit," he explained.

"I've definitely been driving within myself, which is a shame, but you have to around here because [otherwise] you're in the wall.

"It's very difficult for me, but I enjoyed it immensely.”

The big disappointment after scoring the Woking outfit's second Q3 appearance of the season is the realisation of a 15-place grid penalty that drops Jenson to the back of the grid.

"It doesn't matter how many races you've done or not, it still hurts," the 2009 champion conceded.

"They told me yesterday - I was so excited about qualifying because Thursday went really well.

"We both got penalties, Stoffel [Vandoorne] will start 12th because he gains my position and I'll start last.

"We would have both started in the points, so it's a shame," he added. "But hey, it's never easy, is it?”