LOS ANGELES (AP) - Mary Pierce surprised Kim Clijsters 6-1, 4-6, 7-6 (2) at the WTA Championships on Tuesday night in a wildly uneven rematch of their U.S. Open final.

Clijsters beat Pierce in straight sets to win her first Grand Slam title in September. This time, Pierce held a match point in the second set in front of a sparse crowd at Staples Center, but Clijsters reeled off three straight points to even the match. Clijsters was off her game from the start, committing 31 unforced errors and 11 double faults.

Pierce was equally messy, making 21 errors, although she converted five of seven break chances.

Clijsters broke to open the third set and owned a 3-1 lead before Pierce rallied in her first appearance in the season-ending championships since 1999.

Pierce trailed love-40 on her serve before winning five straight points, including a 174-km/h ace, to close to 3-2. Clijsters double-faulted to fall into a 4-4 tie.

Pierce served a 40-love game to go up 5-4, then Clijsters won two straight games for a 6-5 lead. Clijsters won one point on her serve before being broken at 6-6.

Pierce dominated the tiebreaker, winning five of the last six points to close out the match on Clijsters' backhand error.

At 30, Pierce is nearing the end of a dream season in which she reached two Grand Slam finals and won two titles to return to the Top 5 for the first time in five years.

Clijsters, ranked No. 2 in the world, is challenging Lindsay Davenport for the year-end No. 1 ranking. They are separated by 155 points, and whoever has the better showing this week will wind up on top.

Clijsters has won a Tour-leading nine titles this year. The loss snapped her nine-match winning streak in the championships, which she won in 2002 and '03.