Though Andre Ward's six-year winning streak is still intact, the American light heavyweight now faces his biggest test yet.

Ward, a top U.S. medal hopeful, beat Italy's Clemente Russo, 17-9, to advance to the quarterfinals at Peristeri Olympic Boxing Hall. Up next: Russia's Evgeny Makarenko, who has a streak of his own. He hasn't lost at a major international event since 1999.

The Americans finished a 6-1 run through the preliminaries on Wednesday, sending an impressive eight fighters into the second round, with two advancing on byes.

But yesterday, welterweight Vanes Martirosyan lost, 20-11, to Lorenzo Aragon, Cuba's two-time world champion. During the evening session, light welterweight Rock Allen lost, 30-10, to Boris Georgiev of Bulgaria.

Except for the heavyweights, all remaining fighters must win two more matches to reach the semifinals, where a medal is guaranteed.

Tuesday, Ward will fight two-time world champion Makarenko for a berth in the semifinals. Makarenko owns a six-inch height advantage on Ward, as well as nearly nine years of experience in the amateur style.

But Ward, a natural middleweight who bulks up to take on light heavyweights, has power and quickness that have led him to multiple national championships.

"I saw [Makarenko] walk out. He's big," Ward said with a grin. "He's not the first big guy I've fought, though. I've been fighting giants my whole life."

American light heavyweight Andre Ward, right, beat Italy's Clemente Russo.