The Colombian, who joins rivals McLaren next season, took control of the race after the first set of pit-stops and held off the advances of future team-mate Kimi Raikkonen to take the checkered flag.

The victory, by a one second margin, was the first of the season for both Montoya and the team and was the driver's fourth of his Formula One career, which began with BMW Williams in 2001.

Raikkonen hounded Montoya to the finish line but he could not find the speed to overtake and grab victory.

Home favorite Rubens Barrichello, who started on pole ahead of the pair, had to settle for third as he finished the Brazilian race for the first time since 1994.

Thank you, Frank Williams!

Juan Pablo Montoya left BMW Williams as a winner in Brazil on Sunday, even if he had hoped for greater things before the season started.

The Colombian had wanted to take the world champion's number one with him to McLaren next year but that dream was shattered by Ferrari and Michael Schumacher when the championship was still in its infancy.

Williams had looked in danger of drawing a blank for 2004 until Sunday, their last win being Montoya's triumph at Hockenheim in August 2003.

They had struggled with the radical-looking 'tusked' car early in the season, before abandoning the style, and were hit by Ralf Schumacher's absence through injury for six races over the European summer.

On Sunday, at the closest thing to a home circuit for the driver from Bogota, Montoya provided the best parting gift he could come up with, his fourth win for the team.

"It's been four years with Williams, we've had ups, downs and everything and I think to close those four years with a win is unbelievable," he said.

"I really want to thank Frank (Williams)."

The team, fourth in the championship, was duly grateful.

"What a fantastic way to finish the season," said technical director Sam Michael. "He didn't put a foot wrong, the pit crew and the engineers got everything right as well.

"It's been a hard season for us and this is a great reward." Montoya, fifth in the championship after challenging for the title last year, could claim his win at Interlagos was personally long overdue as well.

"It's awesome to finish the season like this," he said after the Colombian and British national anthems, for the winning constructor, had been played.

"It really pumps me up for next year and I'm really looking forward to working with Kimi (Raikkonen) next year. I think the position we are in for next year could be really strong."

Raikkonen, his future team mate who finished overall runner-up last season, was second for McLaren at Interlagos.

"I think it was a tough race," said Montoya. "I came into the race thinking Kimi was going to be the guy that had the chance to win the race.

"Before the race there are always rumors as to who's got more fuel than whom and when I heard how much fuel -- supposedly -- Kimi had I thought 'phew, he'll be hard to beat.'"

From the Directors:

Sam Michael (Technical Director WilliamsF1):
What a fantastic way to finish the season, with a superb drive from Juan Pablo! He didn't put a foot wrong, the pit crew and the engineers got everything right as well. With tricky conditions at the start of the race fuel loads were critical. Ralf also did a good job. Unfortunately he lost some time in the pits, but regardless he didn't give up and overtook a couple of cars during the race. Michelin's intermediate tyre performed well at the start of the race. It's been a hard season for us and this is a great reward for all the people who worked hard in the Grove and Munich factories and at the circuit to turn the FW26 around. Finally, all the best to Juan Pablo and Ralf for the future.

Mario Theissen (BMW Motorsport Director):
This was a great relief for the team after a long and tough season. I am proud of our team's recovery from a difficult situation and we have now come back to former strengths. My compliments to both the drivers who gave everything at their last race for the team. Juan's race was just perfect. This progress is of great importance for our technicians as it is exactly the right motivation for the development of the new car and engine. The tenth victory feels as good as the first one. We are back!