BROOKLINE, MASS., JULY 10 -- Defending champion Andres Gomez won a controversial quarterfinal match over Jimmy Arias today at the U.S. Pro Tennis Championships.

Gomez, the No. 2 seed from Ecuador, beat seventh-seeded Arias, of the United States, 2-6, 7-5, 7-6.

The dispute erupted over the first point of the third-set tie breaker. A lineswoman called Arias' deep shot to the left corner out, then reversed herself. After a 15-minute dispute in which Gomez argued that he stopped going for the ball when he heard the out call, the point was ordered replayed.

It was won by Gomez, who also won the next three points and took the tie breaker, 7-3.

"I was on a roll," said Arias, who had won the previous three points to force the tie breaker. "I lost all the momentum. He just cheated, basically."

"I'm not a cheater," Gomez said.

Gomez's semifinal opponent for the second straight year will be third-seeded Kent Carlsson, who beat No. 5 Joakim Nystrom, a fellow Swede, 6-1, 7-5.

Top-seeded Mats Wilander of Sweden will play in Saturday's other semifinal after beating Tom Nijssen of the Netherlands, 6-2, 7-5. Wilander will meet No. 4 Martin Jaite of Argentina, who defeated sixth-seeded Aaron Krickstein of the U.S., 1-6, 6-4, 6-1.