Current Formula 1 World Championship leader Jenson Button has described his lap to take pole position for this weekend's Monaco Grand Prix as being 'on the edge the whole way round' and 'one to remember' - and now he is bidding to convert it into victory in the race dubbed the jewel in the sport's glittering crown.

The British star's fourth pole in six outings thus far in 2009 is inarguably his most important one, coming as it did around a circuit upon which it is nigh-on impossible to overtake - and coming out of the blue to a certain extent too, with the 29-year-old having struggled from the word 'go' in the Principality on Thursday morning.

Losing time following a brush with the track's unforgiving Armco barriers early on in practice and having not lapped any quicker than fourth place on the opening day, Button looked to be somewhat on the back foot entering qualifying, especially as the winding, tortuous nature of Monte Carlo is known not to particularly favour his traditional driving style. An understeer and grip-afflicted eighth place in the 'low-fuel' Q2 session seemed to confirm that struggle, but a stunning last-gasp effort in the top ten shoot-out enabled the Frome-born ace to pip Ferrari rival Kimi Raikkonen to the top spot by the narrowest of margins at the close.

The scene of a heavy practice accident six years ago that ruled him out of the race, Monaco has never really shone upon Button during his seven previous F1 appearances there, with but a single finish inside the points - albeit in second place - to his name to-date. He hopes that unenviable record will change this weekend.

"It's so important to qualify well in Monaco," he underlined, "and I am really happy to have achieved pole position here today. It means a lot to me - they all do - but this one is so important for the race tomorrow. It was definitely a lap to remember and I was really on the edge the whole way round! It was a real fight today, and I thought that Rubens [Barrichello - team-mate] would have the upper hand in qualifying as he has been so strong all weekend.

"I struggled on Thursday to find a good balance and we had a few issues that needed to be worked on, however we have made some changes since then. I really have to thank everyone at the factory in Brackley and at Mercedes-Benz for producing such a strong and responsive car which allows us to make progress quickly. It's not going to be easy in the race tomorrow as Monaco is just so unpredictable, but starting from pole is without doubt the best position be in."

If you were going to put your money on one of the Brawn GP drivers to steal pole, though, prior to the session it looked like Barrichello might be the safer bet, with the experienced Brazilian - who turned 37 today - outpacing the sister car throughout day one and looking to be the more consistent of the pair. Fourth-quickest in Q2, the S?o Paulista ultimately came up just under two tenths of a second short in third, but with the two heaviest cars inside the top eight on the grid, the Brackley-based ex-Honda F1 outfit certainly looks to be in good shape for race day.

"I had a great lap at the end of the final qualifying session," mused Barrichello, "so Jenson's lap must have been fantastic! I'm very happy with my position for the race tomorrow and really got everything possible out of the car today.

"Of course I'm sorry that I didn't get pole position, but the car has felt really good all weekend and we have a great chance for the race tomorrow. This is my 17th Monaco Grand Prix, but the special feeling that you get from driving around here never changes and it is such a great challenge. It will be a really close and exciting race tomorrow and I'll be giving my all for the win."

"A very good day's work from the team," summarised team principal Ross Brawn, "with great laps right at the end of the final qualifying session from Jenson and Rubens. To achieve pole and third position on the grid in the most important qualifying hour of the season is a real achievement and puts us in a strong position for the race tomorrow.

"Jenson had to work quite hard on his set-up as he has been struggling with the balance and a lack of front grip all weekend, so he knew that the lap had to be extra-special to make the difference and he delivered very impressively. Rubens, as ever, excels around Monaco and he is very well-placed to take the fight to Jenson tomorrow. The cars around us are also looking strong, so it is going to be a very interesting race."