Michael Chang wrecked Pete Sampras's plans for a steady build-up to the French Open with a straight-sets win in the third round of the Italian Open yesterday. Chang ran down the top seed's every shot to earn a shock 6-2, 7-6 (8-6) win and reach the quarterfinals of the £1.53 million Rome tournament.

Once again, Sampras must analyse his game on clay as the start of the only Grand Slam he has yet to win nears.

The world number one attributed a slow start in the first set and the light balls used at the event for his downfall.

"I've gotten off to a shaky start in every match I've played this week," Sampras said. "It feels like the balls are flying through the air and I felt tentative.

"As the match wore on, I started feeling more confident with my shots. In the first I tried to hit my way out of trouble. I relaxed in the second and waited for the opportunities."

Chang, who won their only other meeting on clay at the French Open nine years ago when he took the title, was delighted with his performance.

"I played some good tennis," he said. "I'm pleased to be able to come out and win the match. It's been a long time since I've played him on any court."

Chang moved well after a left knee injury which he suffered in March. "I'm almost 100 per cent. It's taken time and I've needed a lot of treatment, but I'm now painfree," he added.

There were two other surprises, former Wimbledon champion Richard Krajicek defeating sixthseeded Russian Yevgeny Kafelnikov 6-2, 3-6, 7-6 (8-6) and New Zealander Brett Steven beating Spain's Monte Carlo champion, Carlos Moya, 7-5 6-0.