MIAMI: Belgian Justine Henin, playing her fourth tournament since returning from retirement, downed World No 2 Caroline Wozniacki on Wednesday to reach the semi-finals of the Sony Ericsson Open.

Henin, a former World No 1, downed the second-seeded Danish teenager 6-7 (5/7), 6-3, 6-4. In the semi-finals of the hardcourt event, Henin will face 14th-seeded compatriot Kim Clijsters, who beat ninth-seeded Australian Samantha Stosur 6-3, 7-5.

Andy Roddick advanced to the men’s semi-finals with a 6-3, 6-3 victory over Nicolas Almagro. “When you play a lot of matches and kind of play a high level, it feels like everything kind of slows down a little bit,” Roddick said. “Muscle memory takes over a little bit more. I think I’m at that stage right now. Unfortunately with tennis, you have to start over every day.”

Roddick, the 2004 champion, next faces either fourth-seeded Spaniard Rafael Nadal and eighth-seeded Jo-Wilfried Tsonga of France. The top three men’s seeds — Roger Federer, Novak Djokovic and Andy Murray — have all been eliminated. “Obviously you’re surprised any time he loses,” Roddick said of Federer, who lost to Czech Tomas Berdych on Tuesday. “But that’s tennis. That’s why you play.”

Henin, currently ranked 33rd in the world and playing on wild card invitation, has already beaten four seeded players in a row. She’s 16-3 since ending a 20-month retirement in January, and she’ll move back into the top 30 in next week’s rankings.

After her slow start, Henin was dominant on serve in the final set and closed out the 2hr 45min match with a love game. Henin, who had 31 unforced errors in the opening set, said Wozniacki’s variety kept her from finding a groove early.

Henin, winner of seven Grand Slam titles, has never won in Miami. Her best finish here was in 2007, when she lost to Serena Williams in the final. She was playing for the first time against the 19-year-old Wozniacki, who recalled watching Henin play on TV.