World number one Justine Henin brushed aside Czech teenager Nicole Vaidisova to reach the semi-finals of the Eastbourne International grasscourt tournament on Thursday.

Henin, the defending champion at the Wimbledon warm-up event, won 6-2 6-2 in 55 minutes.

Amelie Mauresmo, who will defend her Wimbledon title next week, recovered from a lapse of concentration to beat Israeli sixth seed Shahar Peer 6-3 6-4.

In Friday's semi-finals, Mauresmo will play third seed Nadia Petrova who overcame a back problem and leg cramps in the heat to beat Austrian ninth seed Sybille Bammer 6-7 7-5 6-4 in a match that lasted just under three hours.

Fifth seed Vaidisova, the youngest player in the draw at 18 and an Australian Open semi-finalist in January, has a big serve but when that started to let her down she had no other weapons to use against Henin.

She found herself 5-0 down within 20 minutes, having held only one game point.

Vaidisova broke Henin as the Belgian top seed served for the first set at 5-1 but then surrendered her next serve to love.

Henin, who went 5-2 up in the second set, piled on the pressure as she watched Vaidisova's serve become more erratic.

Though the Czech saved one match point she soon gave Henin a second chance thanks to a double fault, then put a backhand into the net to concede the match.

French Open champion Henin, aiming to win Wimbledon to complete her collection of grand slam titles, will next play eighth seed Marion Bartoli of France who thrashed Russian fourth seed Elena Dementieva 6-1 6-0 in 71 minutes.

DOUBLE FAULTS

Bartoli, inspired by another straight-sets defeat of Dementieva in the French Open third round earlier this month, put the Russian under relentless pressure from the start.

Dementieva, a quarter-finalist at Wimbledon last year, never looked comfortable, struggling to get her first serve in and hitting eight double faults.

Second seed Mauresmo, after taking the first set easily, allowed Peer to break her to go 4-2 up in the second set.

The French world number four was pleased, however, at the manner of her comeback.

"I lost a little bit of intensity at the beginning of that second set so that she was able to break me and I really focused, concentrated and was able to break her back right away," Mauresmo told a news conference.

World number 11 Petrova had three bouts of medical treatment during her marathon against left-hander Bammer, for a back strain and thigh cramps.

The Russian had chances to finish off her match earlier, after going 5-1 up in the deciding set, but Bammer, mother of a five-year-old daughter, saved two match points to hold serve.

Bammer then broke Petrova and held her own serve to pull back to 5-4 but the 24-year-old Muscovite clung on to win.

"I enjoyed the fight between us," Petrova told reporters. "She is a tough competitor."