Unseeded Felix Mantilla of Spain pulled off an astonishing win over in-form Roger Federer of Switzerland on Sunday to win his first-ever Master Series event.

Mantilla, who snapped the fourth seed Federer's 12-match winning streak with a 7-5 6-2 7-6 (10-8) triumph in 2 hours and 41 minutes in the final of the Italia Masters clay-court event in Rome, broke down in tears during his speech on court afterwards.

It was his 10th career title, first since Palermo in September 2001 and moves him to sixth place in the ATP Champions Race.

The loss was Federer's first since falling to Albert Costa in the quarter-finals at Miami in March and prevented him from winning his fourth tournament of the year, which would have tied him with Andre Agassi for the ATP lead.

Mantilla, the first unseeded winner in Rome since Australia's Martin Mulligan in 1963, saved 14 of 17 breakpoints during the match and won six of 11 breakpoints on Federer's serve.

He was understandably delighted with his display.

"Rome has given me so much, the feelings I have right now after winning this title I will never forget for the rest of my life," he said.

"It is a Tennis Masters Series event, and for sure it's the biggest victory of my career. That is going to give me a lot of confidence for the future.

"I think I am still young. I don't know the age, but inside I'm young. I'm mentally strong. And I hope that makes me work harder - if it's possible - and try to do something else in tennis.

"I was working hard on my physical training, and my coach told me that I was playing unbelievable since the first week of the year. That makes me feel well on court."

Although disappointed with seeing his brilliant form come to an end, Federer said Mantilla deserved to win.

"I'm happy I was the first Swiss player in the Rome final and I'm happy with my tournament here," said Federer, who is nicknamed the 'Federer Express'.

"Mantilla beat a lot of good players this week and deserved to win this title.

"I missed too many chances in the first set, I don't know how many breakpoints I had. It's a real shame. After a while everything was going his way, I almost felt he was destined to win this tournament.

"It's always terrible when a match starts this way. You don't win your breakpoint out of one of the first five or so, it gets to your head mentally.

"I always played well till the breakpoints, then I felt like I didn't understand why, you know, because I thought I was staying aggressive."