New York ? Lleyton Hewitt’s fighting spirit has helped him become a Grand Slam champion and the world’s top-ranked player. It also gets him into trouble.

He’s been fined for yelling at linesmen, lost a point for throwing a ball near an official and was criticized for what was perceived as a racially influenced outburst during a match in last year’s U.S. Open.

He’s the defending champion and seeded first at the U.S. Open, which starts today. Neither Hewitt nor Venus Williams, who is trying to become the first woman to win three straight U.S. Opens since Chris Evert took four in a row from 1975-78, plays on the opening day.

Top matches today include Williams’ younger sister, top-ranked Serena, against Corina Morariu, who’ll be playing her first Grand Slam match since returning to the tour after fighting leukemia for more than a year.

Serena is aiming for her third consecutive major title, after beating Venus in the finals of the French Open and Wimbledon.