WIMBLEDON, England -- An 18-year-old qualifier from Croatia shook up Wimbledon on Tuesday with the first major upset.

Mario Ancic, ranked No. 154 and playing his first Grand Slam match, outplayed seventh-seed Roger Federer 6-3, 7-6 (2), 6-3 on Centre Court.

Fifteen minutes later, there was another upset when 71st-ranked Flavio Saretta of Brazil marked his Wimbledon debut by outlasting Australian Open champion Thomas Johansson, the eighth seed, 6-7 (2), 6-4, 7-6 (4), 3-6, 12-10.

Top-seeded Lleyton Hewitt, looking for his first Wimbledon crown, got off to a strong start with a 6-4, 7-5, 6-1 win over Jonas Bjorkman.

Tim Henman, the bookies' favorite for the men's title, swept French qualifier Jean-Francois Bachelot 6-1, 6-3, 6-2 as he began his latest attempt to become the first British male champion since Fred Perry in 1936.

But the stars of the day were Ancic and Saretta.

Ancic drew immediate comparisons with Goran Ivanisevic, last year's champion who is back home in Croatia recovering after shoulder surgery.

Both men are from the Adriatic coastal city of Split, and the 6-foot-4 Ancic is tall, skinny and lanky like Ivanisevic. While Ivanisevic is left-handed, the right-handed Ancic also has a booming serve and plays serve-and-volley on grass.

"I had nothing to lose,'' Ancic said. "I knew I can play, I'm young. I believe in myself, I just went out and tried to play.''

Ancic said he spoke by phone with Ivanisevic on Monday to discuss tactics for the match.

"He's always been good to me, sometimes I felt he was my bigger brother,'' Ancic said.

Federer reached the quarterfinals last year, ousting seven-time champion Pete Sampras in the fourth round, and has won two titles this year. But he was dominated by Ancic, the second-youngest player in the draw and playing only his second tour-level match of 2002.

A finalist at the Wimbledon juniors in 2000, Ancic broke Federer three times and lost his serve only once, hitting serves at an average speed of 120 mph and a fastest delivery of 127 mph

When Federer missed a passing shot to end the contest, Ancic pumped his fists and let out a scream. He then held up his arms to the crowd and belted a ball into the stands.

"I feel great,'' Ancic said. "I cannot feel better I think.''

Asked whether he should be considered the new Ivanisevic, he said, "No, Goran is Goran. He's unique. I'm Mario.''

Saretta, meanwhile, outdueled Johansson in 4 hours, 22 minutes on Court 18 in only the second grass-court match of his career. The fifth set alone lasted 97 minutes.

The Brazilian, who turns 22 on Friday, came in with a 2002 match record of 8-9. Johansson, who won his first Grand Slam title in Melbourne in January, had twice reached the fourth round at Wimbledon.

"It's probably the best match that I've played in my life,'' Saretta said.

Hewitt needed just 1:56 to put away Bjorkman, a solid grass-courter who won a Wimbledon tuneup last week at Nottingham.

Hewitt had pulled out of a tournament in the Netherlands last week with a stomach virus but showed no signs of weakness Tuesday. He made only seven unforced errors, while producing 30 winners, and broke Bjorkman six times while losing his own serve only once.

Hewitt, the reigning U.S. Open champion, has never made it past the round of 16 at Wimbledon, but Tuesday's performance showed he will be tough to beat.

On Court 1, fans wore Union Jack flags and hats, held up the red-and-white English flag of St. George and shouted 'Come on, Tim!'' as No. 4 Henman beat the 165th-ranked Bachelot.

Henman, a semifinalist in three of the past four years, had only three unforced errors in the match and got a standing ovation as he left the court. He will face another qualifier in the second round and is projected to meet Hewitt in the semis.