Juan Martin del Potro squeaked into the semifinals of the ATP World Tour Finals in London by beating Roger Federer, 6-2, 6-7 (5), 6-3, yesterday — the slimmest possible margin to advance and knock Andy Murray out of the tournament.

The result means Del Potro and Federer both advance after a three-way tie in Group A, with Murray's elimination literally coming down to the last game after three rounds of group matches.

All three players finished the round-robin stage with two wins and identical 5-4 set records, but Murray had the lowest percentage of games won. Had Del Potro lost just one more game against Federer, Murray would have advanced at the Argentine's expense.

Murray beat Fernando Verdasco, 6-4, 6-7 (4), 7-6 (3), earlier yesterday.

The complicated tiebreaker system left even the players uncertain about who had advanced when the last match was over.

"I asked Juan Martin myself at the net, 'Did you make it or not?' " Federer said. "He said, 'I don't think so.' ... Of course, you got to feel sorry for the guy who didn't make it. At the same time, Del Potro beat the No. 1 player in the world in the group, and I guess also deserves to go through. There's only two places, and that's the way it is."

In Group B, Robin Soderling has already clinched a semifinal spot, while Nikolay Davydenko and Novak Djokovic are still in contention heading into today's matches. Rafael Nadal was eliminated after two straight losses.

GOLF

IRELAND OPENS WITH A 58 IN WORLD CUP

Rory McIlroy and Graeme McDowell shot a better-ball 58 yesterday to give Ireland a three-stroke lead over Argentina after the first round of the World Cup of Golf at Henzhen, China.

Argentina's Tano Goya and Rafael Echenique were at 11-under 61, with Japan another shot behind. The United States pair of Nick Watney and John Merrick was tied for 15th at 5-under 67 after four birdies by Watney.

Defending champion Sweden was tied with Italy, Canada and South Korea six strokes off the lead in the $5.5 million tournament at the Mission Hills Golf Club. Today's second round will be alternate-shot, as will Sunday, while tomorrow's will be better-ball again.

Aiming to win Ireland's third World Cup, McDowell and McIlroy each birdied six holes on the 7,251-yard course. McIlroy eagled the par-5 15th hole.

SOCCER

CHILE FACING OUSTER FROM WORLD CUP

Chile could be kicked out of the World Cup unless the Chilean club Rangers drops a court case by Dec. 3 contesting its disputed demotion to the second division of the national soccer league.

CONMEBOL, the governing body of South American soccer, said yesterday it was notified by FIFA about the possible sanction.

Rangers were deducted three points for using six foreign players — the limit is five — in a league match on Nov. 8. The three points cost them relegation to the second division, and last week they appealed the case to a Chilean court.