LONDON - When Roger Federer hangs up his rackets his sublime artistry will be his lasting legacy but Saturday's win over Juan Martin del Potro at the ATP World Tour Finals showed when the chips are down he can also fight like an alley cat.
For most of Saturday's Group B shootout for the right to play Rafa Nadal in the semi-finals, the 17-times grand slam champion was heading for the exit but the Swiss refused to budge under the Argentine's brutal power and clawed out a thrilling 4-6 7-6(2) 7-5 win.
It has not been a vintage season for Federer, who has dropped to world number seven, but he is ending it on something of a high and insists he will come out swinging when he faces world number one Nadal for a place in the final.
"I feel very happy and very upbeat," Federer, who was behind all the way against del Potro until 6-5 in the deciding set, told reporters. "I'll give it one more big shot here tomorrow and hopefully I'll make it to the finals."
Federer's enthralling victory over del Potro sealed the runners-up spot in Group B behind Novak Djokovic who will face Federer's compatriot Stanislas Wawrinka in what could be a landmark day for Switzerland.
Wawrinka would have enjoyed the sight of Djokovic grafting for more than two hours late on Saturday to beat Richard Gasquet 7-6(6) 4-6 6-3 in a dead rubber, albeit one that earned the Serb another $142,000, 200 ranking points and extended his winning streak to 20 matches.
Federer, who has won only two of his last nine matches against Nadal, will have to go up a notch after a display of wild fluctuations against del Potro, an opponent to whom he had lost three times in a row before a confidence-boosting victory at last week's Paris Masters.
An error-strewn first set saw him go 5-1 down and he always seemed to be fighting himself as well as his opponent before his class finally shone through.
"There was a lot of coming from behind, trying to get back into the match, and it was amazing that I was able to pull it off," a delighted Federer said.
"I could never play free-flowing tennis. I fought hard, maybe got a bit lucky at times."