BERLIN (AP) -- Venus Williams struggled all day and Justine Henin slammed winners. The result was the Belgium teen-ager's biggest career win Thursday at the German Open.

The rising 18-year-old needed four match points but stunned the reigning Wimbledon and U.S. Open champion 6-1, 6-4 to reach the fourth round of the $1.185 million event.

``Not every day is your day. What can I say?'' Williams said. ``If she can play like that every time, she should be No. 1. I don't think she's ever played a match like that in her life.''

Williams lost for the first time since Feb. 17 in Nice, France, a streak of 14 matches, although she did pull out of the Indian Wells, Calif., semifinal match against sister Serena in the midst of that run.

``She may have not played great, but I played well and didn't let her play the way she likes,'' said Henin, who started 2001 with a 13-match winning streak and titles at Canberra and the Gold Coast in Australia.

``I think in the past I've had too much respect for the big names, but today I was determined to go out and hit winners,'' she added.

The loss by Williams spoiled a showdown with top-seeded Swiss player Martina Hingis, who rolled past France's Nathalie Dechy 6-3, 6-1 to reach the quarterfinals.

Williams, coming off two straight titles, made numerous unforced errors until Henin drove a backhand deep into the corner, then easily put away the American's weak reply to end the match in 73 minutes.

``Sometimes she made some great shots, I missed a few, it takes both,'' said Williams, whose hopes of passing Hingis for the No. 1 ranking at the French Open starting May 28 also were set back.

``It will happen when it happens. We'll see how it goes. Maybe I can pick up a lot of points at the French Open,'' Williams said.

Henin, ranked a career-high 18th, pounded Williams' backhand, deciding several games with sizzling shots to that side.

But the American, who has a 22-3 record this year, also helped the teen-ager's cause with mistakes, including a double fault that put the Belgium teen-ager up 5-3 in the second set.

Williams will now skip next week's clay court event in Rome and return to the United States to prepare for the French Open. But she was nonetheless happy with her game after winning last week in Hamburg in devastating style, losing just 12 games in four matches.

``I had some good experiences on clay, and enough practice, too, for the French Open,'' she said.