It was the second win of Montoya's 41-race career and the first of the season for BMW-powered Williams, whose last triumph in the Mediterranean principality was in 1983 with Finland's Keke Rosberg.

Finland's Kimi Raikkonen [ Images ] finished runner-up for McLaren [ Images ], 0.6 of a second behind Montoya, to stretch his championship lead over Ferrari's [ Images ] world champion Michael Schumacher [ Images ] to four points after seven races.

Raikkonen has 48 points, Schumacher 44.

Schumacher finished a close third, his hopes of equalling the late Brazilian Ayrton Senna's record of six Monaco wins in tatters after a highly strategic race on a tight street circuit where overtaking is almost impossible.

It was the first time since Ferrari introduced their new F2003-GA car last month that the Italian team had been beaten and ended Schumacher's quest for a fourth victory in a row after a poor start to the season.

Montoya's team mate Ralf Schumacher was fourth, after starting from pole, with Spaniard Fernando Alonso [ Images ] fifth for Renault [ Images ] ahead of Italian Jarno Trulli [ Images ] in the French manufacturer's other car.

McLaren's David Coulthard [ Images ] was seventh, a disappointment for the Scot who has won twice in the last four years, while Brazilian Rubens Barrichello [ Images ] claimed the final point for champions Ferrari.