Newey said that McLaren knew Monaco would provide them with their best opportunity to win a race this season, but that they did not expect it to happen.

"It has been a tough season so far, so to get a good result here is really fantastic," Newey said.

"It was the race at which we felt we had the best chance, the one that most suited our car, so it's nice to get the job done.

"Coming here, we hoped we'd do well, but we didn't expect to win, so it's a happy surprise."

McLaren have struggled this season because their Mercedes engine is down on power compared to their rivals from Ferrari and Williams-BMW.

But the tight, twisty nature of the Monaco track makes that less of a handicap and Coulthard was able to benefit from McLaren's strong chassis and some good Michelin tyres.

The French rubber had the advantage over Ferrari's Bridgestones in qualifying and Coulthard and Juan Pablo Montoya were able to take advantage by securing the front row of the grid.

However, the tables were turned in the race, when Michael Schumacher's car was the fastest and Newey praised Coulthard's performance.

"Michael car was quicker but David did not put a foot wrong," he said.

Coulthard, who lost a chance of victory in Monaco last year when his electronics stranded him on pole position, played down his part in the win.

"It's unbelievable. I feel fantastic," he said.

"We have had a difficult start to the season, and it was looking pretty difficult for us to win a Grand Prix, but we had our hopes pinned on Monaco and getting a good result.

"The traction control caused me some problems last year, but it worked fantastically this year and after that it was just a case of keeping it away from the barriers."

Coulthard had a worrying time early in the race when his car seemed to be losing oil.

"I felt for a few laps as if things were tightening up a little bit and thought: 'This doesn't look good,'" he said.

"But the team said everything was OK and thankfully it was."

McLaren boss Ron Dennis said: "I'm very pleased for the team. It's still going to be tough for the rest of the year but it's great to win here."