* Del Potro wins first meeting since epic Olympic clash
* Argentine claims fourth title of the year (Adds detail, quotes)
BASEL, Switzerland, Oct 28 (Reuters) - Juan Martin del Potro, beaten in his six previous meetings with Roger Federer this year, turned the tables on the world number one to win a memorable Basel ATP final on Sunday.
Two of the three sets went to tiebreaks with the towering Argentine eventually winning 6-4 6-7 7-6 to claim his second title in a row following his win in Vienna one week ago and his fourth of the year.
The two were meeting for the first time since their epic Olympic Games semi-final when Federer eventually won in a 36-game final set.
There was no quarter given this time, either, in a match featuring long baseline rallies peppered with some stunning winners from both players.
Del Potro also lost to Federer in the quarter-finals of the Australian and French Opens, the Rotterdam final, the Indian Wells quarter-final and the Dubai semi-finals this year.
"My serve worked, my forehand worked. It was really close, but this time in my favour, finally, after six losses and two big losses at the Olympic Games and Roland Garros," world number eight Del Potro told reporters.
"It's my turn," added Del Potro, who has edged his way back towards the top despite a series of injuries including a wrist problem which forced him to miss most of the 2010 season.
"Very few players beat Federer and it shows me that I am getting closer to get the ones at the top."
Del Potro, who has beaten Federer three times in 16 attempts including the 2009 U.S. Open final, managed the only service break of the entire match in the fifth game of the first set.
Federer, who has won five of his seven finals in his Basel hometown, had to wait until the second game of the second set for his first break point which he failed to convert.
Del Potro had his only other break point of the match in the 11th game but a tiebreak was always on the cards, with the Swiss winning 7-5 to level the match after Del Potro had saved two set points.
That seemed to swing the match in Federer's favour and the Swiss had three break points in the third game of the third set, but Del Potro held his nerve each time.
Leading 6-5, Del Potro had a glimmer of victory in the 12th game as he led 30-15 but Federer reeled off three aces in a row to send the set to another tiebreak.
At that point, the Swiss made some rare mistakes as he mis-hit a shot into the net before over-hitting a forehand on match point.
"He missed a couple of shots but he was hitting really close to the line and that is what you need to do to win these matches," said Del Potro.
Federer said: "I had my chances in the third set but he was able to come out of that one and I didn't play a good tiebreak. That is the story of the match." (Editing by Justin Palmer/Mark Meadows)