Lewis Hamilton returned to the scene of his maiden Formula One victory today and admitted he is still amazed he won last year's Canadian Grand Prix.

The McLaren driver regained the lead in the drivers' championship two weeks ago with the sixth F1 win of his short career at Monaco.

Now he is back at the Circuit Gilles Villeneuve in Montreal, where 12 months ago he claimed a first pole position and emerged from an incident-packed race to take the chequered flag.

"I was happy I got my first pole position but I wanted to convert it to a win," Hamilton said as he prepared for today's first practice session.

"Then we had all those safety cars. I had this big gap, a safety car would come out and then another gap and another safety car. So I was thinking, 'Am I really supposed to be winning this race?' But I still managed to pull it off. It was a spectacular win and I was thrilled about it.

"Even now, looking back on last year, I don't even know how I did it. It's so hard to be consistent."

Hamilton holds a three-point lead over world champion Kimi Raikkonen but played down his success in Monaco.

He said: "It's nice for me but I don't think it makes much of a difference.

"The team have been working so hard and they deserved it more than anyone. For me, I don't really need a confidence boost. It was nice to have the win but I'm not going to get overly excited about it."

Raikkonen, meanwhile, has admitted he is considering retiring when his contract with Ferrari expires at the end of next season.

Speculation has been mounting as to who will drive for Ferrari in 2010 and the Finn said: "I haven't made any decision as to whether I will keep going or not. We will wait and see during what happens. "

Raikkonen, 28, added that the enjoyment he got from motor sport had to outweigh the negatives he perceived in F1.

"I wouldn't stop if I thought I would miss it," he said. "I don't know what's going to happen after next year.

"I'm going to race as long as I enjoy it. It can be the end of next year, it can be in four years. It's too early to say. But it's purely if I like it or not.

"When there are more things that you don't like about it than you do, then it's time to stop."