Wimbledon champion Venus Williams was pushed to the limit before beating third seed Jelena Jankovic of Serbia 4-6 6-1 7-6 on Wednesday to reach the U.S. Open semi-finals.
Twice champion Williams, the 12th seed, belted a forehand winner to capture the third-set tiebreak 7-4 and set up a clash with top seed Justine Henin on Friday.
Jankovic charged into a 4-1 lead after claiming two service breaks in the hard-hitting first set. She gave one break back but held serve in the 10th game to clinch it.
Williams raised her level and her aggression in response, breaking the Serb in every one of her service games in the second set to draw level.
The American poured in 60 winners against 17 for Jankovic, also registering 56 errors with her all-out attack. She charged the net 55 times, winning 39 points in the process.
"I wanted to come in today," Williams told reporters. "I got lobbed a few times. I got passed a few times. But ultimately I think it really made a difference because I was trying to move forward."
The pressure-packed third set stayed on serve until the tiebreak, although Jankovic had a break point in the eighth game and challenged the American through a deuce game in the 12th before Williams held.
Williams moved into a 5-1 lead in the tiebreak after a series of forehand errors by Jankovic, who clawed back to 6-4 before the Wimbledon champion cracked her winning forehand to end the two-hour, 27-minute match.
"She's a very good competitor, and anyone has to play a lot of balls against her," Williams said of the Serb's ability to stay in rallies. "I just went for it all the time, nonstop and it paid off."
"Well done to Venus," Jankovic said. "She played unbelievable. She fought well. She deserved to win."
Williams had lost her last three matches to Jankovic.
"Jelena is an unbelievable competitor," she said. "It went the distance. It was awesome."
Williams said she would love to avenge her sister Serena's loss to Henin in the quarter-finals.
"I wasn't happy with the result at all, to say the very least," she said. "I was sad that Serena lost because I didn't like to see her so upset. I definitely have to try to win for Williams."
Fourth seed Svetlana Kuznetsova of Russia, the 2004 champion, will play sixth-seeded compatriot Anna Chakvetadze in the other semi.