Hewitt has easy start in Adelaide

Hewitt has slipped to number 20 in the world rankings

Lleyton Hewitt came through his first singles match in three months when Janko Tipsarevic retired from their match at the Adelaide International.

Hewitt was 6-1 4-2 up when Tipsarevic retired with a thigh injury.

The tournament sees the introduction of a round-robin phase that will feature in a number of ATP events in 2007.

Top seeds Novak Djokovic and Richard Gasquet were in good form, Djokovic thrashing Jan Hajek 6-0 6-1 and Gasquet hammering Florian Mayer 6-2 6-1.

Third seed Radek Stepanek went down 6-4 6-4 to Vincent Spadea.

"I played a really good first match today," said 19-year-old Serb Djokovic.

"He didn't play his best but I didn't allow him to play his game and I was in control. I just hope I will continue the same way tomorrow.

"I am just going to play my game, to be in control and be aggressive. That is how I've played all my life."

Hewitt was dubious about the extent of Tipsarevic's injury.

"After the injury break, I still felt like I was moving him around the court and coming up with some decent shots," said Hewitt.

"There was one backhand he rifled up the line - if he had that bad a groin, I don't know how he would have pulled that off.

"I had my game plan. I wanted to get away with a straight-sets win and I was able to do that."