London - Roger Federer insists that winning his record sixth title at the ATP World Tour Finals was one of the best moments of his career.
Federer has amassed a whole host of magical memories during a remarkable career which has included a record 16 Grand Slam titles.
But, after a frustrating year which saw him fail to win a major and slip to fourth in the rankings, Federer was over-joyed to beat Jo-Wilfried Tsonga in the final of the end-of-season showpiece at London's O2 Arena.
"It feels very special indeed." Federer said. "I've been trying to block it out for the entire tournament but now it's a reality that I've been able to win six titles and it's an amazing feeling.
"I know it's one of my greatest accomplishments. I'm extremely happy and extremely proud.
"This is definitely an amazing finish to the season. I've never finished so strong.
"I used to be famous for not being consistent. I think this one proves that I was able to be successful for a long period of time."
Federer's victory took him past Pete Sampras and Ivan Lendl's tally of five Tour Finals crowns and also equalled Lendl's record 39 match wins in the event.
The 30-year-old, who ends the year third in the world, admitted Tsonga had given him a tough test, which only added to his sense of relief when he finally sealed the win.
"I thought I played well but could I have won it easier? I guess. I had it in my hands," added Federer, who captured his 70th title in his 100th final.
"I had a chance to go a double break up in the second set. I had chances to serve it out and had chances in the tie-breaker.
"I had to go through the third set which was tough but eventually I made it which felt probably even better. The relif was amazing.
"I still don't feel like I'm better than Pete Sampras or Lendl for that matter. I believe they are some of the all-time greats. I'm just happy to be compared to them."
Although Tsonga pushed Federer all the way to the wire, he had no complaints about the final result.
"I fought as hard as I could but he was better than me in the first set and also in the second. I just took the first set point in the tiebreak," Tsonga said.
"I think he played better than me also in the third set. So I was a bit lucky to play three sets on Sunday.
"Of course it's better to win but I gave everything. I can look at myself in the mirror and say, 'Yeah, you fought for everything'. I'm just happy I had a good week."
Since beating Federer from two sets down in the Wimbledon quarter-finals in June, Tsonga has lost four in a row against the Swiss star, including twice at this week's Tour Finals.
"It's tough because he's the best player indoors at the moment and maybe the best player ever," Tsonga said. "He's playing well. That's it."