2011 Canadian Grand Prix winner did not get his defence off to the best of starts at the Circuit Gilles Villeneuve on Friday, as not one, but two, gearbox changes ate into his track time.

The Briton, who staged a stirring back-to-front recovery before forcing Sebastian Vettel into a rare mistake in last year's race, had hoped to match McLaren team-mate Lewis Hamilton in pacing the two Friday free practice sessions but, instead, was forced to cool his heels in pit-lane for much of the day.

Complaining of a lack of grip in the 90-minute morning session, Button was told that the problem was actually an oil leak from the gearbox, which was depositing its load onto the clutch and causing it to slip. Repairs took up the remainder of the session but, just as it was hoped that the 2009 world champion would be able to make up for lost time after lunch, further gremlins raised their heads.

"For Jenson, clearly, today was rather troubled, albeit through no fault of his own," team principal Martin Whitmarsh confirmed, "He suffered an oil leak in this morning's session, which necessitated the removal and re-fitting of his gearbox. Then, prior to this afternoon's session, we diagnosed another problem and as a result we had to change his gearbox yet again.

"Consequently, he lost a lot of running time today - and then, when we finally got him out onto the track with only 18 minutes of P2 to go, he encountered quite a bit of traffic and was unable to get a decent run in the few laps available to him. Still, hats off to his mechanics, who did a splendid job to remove and replace the back-end of his car, not once, but twice, today."

Despite suggestions to the contrary, McLaren will work with Button to find a suitable qualifying set-up during Saturday morning's final free practice hour, and the Briton remains unfazed when it comes to securing another strong result on race day.

"The delays stopped us from doing any high-fuel running or any set-up work simply because we had to get out on the circuit and get some laps in," Button lamented, "It meant we didn't put a set-up on the car that felt quite right, but I'm not too worried - the car has been working well and Lewis has been quick all day, so there's a lot of good information for us to look at for tomorrow."

Confirming that he enjoyed the challenge of the Circuit Gilles Villeneuve, Button insisted that he only needed a little more luck on Saturday to move up from his overall tenth place on the practice charts.

"Of course it hurts, as you cannot do any high-fuel running, and you can't do any set-up work when you change the gearbox," he told the official F1 website in a later interview, "We have to see where the car is now in FP3 but, luckily, we did collect some data in the Friday running that will help us for qualifying. For me, it is more important to run low fuel and get a feeling for the tyres. Friday was not perfect, but we've done worse and still have been able to change course. I believe that we can still have a good weekend, that things definitely look positive."

Button confirmed that, after a couple of frustrating rounds, he had his sights firmly set on securing a good haul of points in Canada.

"One thing is for sure, we will not be able to win every grand prix from here on till the end of the season, as this is simply not how this season is working," he pointed out, "For us, it is important to constantly get double-digit points.

"For me, the last few races were more like stop and start again, as I had two non-finishes and two points only in Barcelona. It has been a pretty bad stretch in terms of gaining points, and I need to turn this fact around. [However], I am very positive to be able to do exactly this, and I have some great memories about Montreal....

"I have to try and achieve some big points, not only here, but at the next few races. I'm quite a bit away from the leader, although the gap is not massive. There are about 150 points up for grabs, and I think the leader has roundabout 80 points [in hand]. Doing well at the next few races, I could be right back in the mix."