KEY BISCAYNE, Fla. — Defending champion Novak Djokovic went into a funk after being warned for taking too much time between points today, then blew a third-set lead to lose his opening match at the Sony Ericsson Open.

Qualifier Kevin Anderson, a 6-foot-7 former NCAA doubles champion at Illinois, beat the third-ranked Djokovic 7-6 (1), 3-6, 6-4.

Djokovic won his first Grand Slam title at this year's Australian Open and was coming off a title at Indian Wells last week. But he struggled from the start against Anderson and was rattled by the warning from a chair umpire.

Serving at 2-0 in the third set, Djokovic won the next point after the warning to reach deuce, then lost 13 points in a row. Jeers from the crowd further agitated him, and by the time Djokovic collected himself, Anderson was up a break at 3-2.

Anderson, a big-serving South African, played for three years at Illinois and won the 2006 NCAA doubles title. He turned pro last year and is 6-2 this year, which has lifted his ranking to No. 122.

In women's play, defending champion Serena Williams and top-ranked Justine Henin won their opening matches in straight sets.

Williams, a four-time tournament champion, beat Edina Gallovits 6-1, 6-2 for her ninth win in 10 matches this year.

"I love playing here," said Williams, who lives nearby in Palm Beach Gardens. "I love having all my friends come and see me play. It's like playing at home. So I think any time you play at home, like the (New England) Patriots playing at home, you always have the extra oomph."

Henin defeated Angelique Kerber 6-4, 6-2, showing no signs of the knee injury that troubled her at the start of the year. The Belgian hit 40 winners to only eight for her 80th-ranked opponent in raising her record this year to 13-2.

Henin began the year with pain in her right knee and considered surgery before deciding to treat the injury with cortisone and rest.

"I feel much better physically today than I did a few weeks ago — that's for sure," Henin said. "So we could see it in my serve. ... I can play with my forehand again, and I feel that everything is better now."

In other men's action, ninth-seeded James Blake defeated Andreas Seppi 7-5, 6-3.