Rafael Nadal won a record fourth straight Monte Carlo Masters title after beating world number one Roger Federer 7-5 7-5 in a tense final.

With the victory, Nadal breaks Ilie Nastase's Open era record set from 1971-1973 and becomes the first man since New Zealand's Anthony Wilding in 1914 to win four straight crowns in the Principality.

The world number two, seeking his first ATP title since July of last year, played the entire match on a razor's edge, breaking back four times to once again deny the top-seeded Swiss in their third straight final meeting in Monaco.

"It's unthinkable, winning here for the fourth year in a row," Nadal said.

"But Roger played a great match. We always have good finals."

Federer looked the more aggressive of the two at the start of the match, pouncing on an early chance to break the 21-year-old Mallorcan in the first game.

But a series of unforced errors from the Swiss allowed Nadal to break straight back in the very next game.

The pair traded breaks again in the seventh and eighth games as Federer struggled to consolidate any sort of advantage with Nadal capitalising on a series of fortunate let cords and stumbles by the Swiss.

After a love-service hold in the 11th, Nadal rushed ahead 40-15 on Federer's serve before confirming the opening set at the first attempt by dragging a perfectly-placed backhand pass across court and right inside the line with Federer caught staring at the net.

Federer, who won his first title of the season last week at the claycourt Estoril Open in Portugal, seemed undeterred by the way in which Nadal took the opener, again starting the second set with a break of serve.

The Swiss then began to play perhaps his best tennis of a very difficult season reeling off the next three games to claim a seemingly insurmountable 4-0 second-set advantage.

But Nadal, who had not dropped a set in Monte Carlo since beating Federer three sets to one in the 2006 final, showed that he was keen to maintain his near-perfect record at one of the oldest claycourt events on the ATP Tour.

The Spaniard started to match Federer's early second-set form just as the top seed, who has been struggling to fully recover from glandular fever since the start of the year, was beginning to wear down.

He held his next service game comfortably to return to the scoreboard before breaking back for the third time in the match thanks to a critical Federer unforced forehand error - one of 44 unforced errors from the world number one.

After Nadal blazed through another love-service game the onus was clearly on Federer to show he could halt the Spaniard's progress, but Nadal broke his rival to love to win his fourth straight game and move within striking distance of the title.

Federer steadied himself by holding to 30 with a fine stretch volley winner at the net in the tenth game, but Nadal then outdid the Swiss with his own gorgeous display of volleying to earn a third successive love-service game and go ahead 6-5.

The 12-time Grand Slam champion Federer then blew two chances to send the set to a tie-break before gifting away the victory with back-to-back errors as Nadal collapsed into the soft Monaco dirt in glee for a fourth consecutive year.

Nadal improves his record in the Principality to 24-1 and claims his tenth Masters Series shield to move within four of Federer's leading total among active players.

The 21-year-old Spaniard has now lost only one match on clay since February 2005, the lone defeat coming against Federer in the final of last year's Hamburg Masters.

Federer, who was nearly eliminated in the second-round of the tournament after being made to come back from a 5-1 third-set deficit against Spanish journeyman Ruben Ramirez Hidalgo, took confidence from his performance against the three-time French Open champion.

"He's a tough player on clay. Maybe my attacking game did not work so well," he said. "I'm still close (to beating him though). It's not getting much easier but I am right there and it's a good thing."

"I am coming back strong and am happy the way things are now.

"A few weeks ago I was still in a bit of doubt."

Jeremy Stahl / Eurosport