Justine Henin and Kim Clijsters both survived scares before booking semi-final berths in the Brisbane International.

Henin, playing her first tournament since retiring from the sport in May 2008, looked on track for an easy victory after breezing through the opening set 6-2 against seventh seed Melinda Czink.

But the Hungarian, who is ranked 37th in the world, hit back to claim the second.

The third set went the distance, with Czink fighting back from a break down before saving two match points at 4-5 and then forcing a tie-break.

But Henin's class and experience prevailed as she closed out the match 6-2 3-6 7-6 (7/5) in two hours 20 minutes.

The Belgian star will now play third seed Ana Ivanovic in the semis after she defeated Russian Anastasia Pavlyuchenkova 6-2 7-6 (8/6) earlier today.

The Serbian glamour girl was in control from the outset, breaking her opponent twice on her way to an easy first set.

She carried that momentum into the second set, winning the first four games before Pavlyuchenkova mounted a comeback to force a tie-break.

The Russian raced out to a 4-1 lead in the breaker, but the world number 21 was not to be denied as she saved a set-point before closing out the match in just under an hour and a half.

Clijsters, meanwhile, was also made to work hard in her quarter-final but eventually edged a rollercoaster clash with Lucie Safarova 6-1 0-6 6-4 at the Pat Rafter Arena.

The Belgian world number 18 broke her opponent twice en route the first set, but five double faults in the second helped Safarova get back on level terms.

The Czech could not maintain that sort of form and conceded an early break in the deciding set, but still made Clijsters work hard for her win.

Clijsters will next face German Andrea Petkovic, who secured her last-four spot with an upset 6-4 6-2 victory over fourth seed Daniela Hantuchova of Slovakia.

In the men's tournament, second seed Radek Stepanek of Czech Republic was too strong for American Wayne Odesnik in their quarter-final encounter.

After edging a tight first set on a tie-break, the defending champion powered to a 7-6 (7/2) 6-1 triumph.

The other American in action today fared no better, with third-seeded Frenchman Gael Monfils coming from a set down to stun James Blake 3-6 6-3 6-4 in one hour and 44 minutes.

Stepanek and Monfils will meet in the semi-finals, with the two other spots in the last four up for grabs tomorrow when top seed Andy Roddick takes on Richard Gasquet and fourth seed Tomas Berdych faces eighth seed Thomaz Bellucci.