Top-seeded Roger Federer of Switzerland and fourth-ranked Croatian Ivan Ljubicic have won their Red-Group round robin matches at the Tennis Masters Cup tournament in Shanghai.

In the opening match Tuesday, Federer battled back from a loss in the opening set and survived three match points in a second-set tiebreaker to beat number-five Andy Roddick of the United States, 4-6, 7-6, 6-4.

Federer has now won eight-straight matches against Roddick and improved his Red-Group record to 2-0, while Roddick drops to 1-1.

In the late match, Ivan Ljubicic also lost his first set before rallying for a hard-fought 5-7, 7-6, 7-5 victory over number-seven David Nalbandian of Argentina. Ljubicic is 1-1 in the group while Nalbandian drops to 0-2.

The lucrative season-ending event features the top-eight players in the world rankings, broken down into two groups of four players each. The top two players from each group advance to Saturday's semifinals, with the winners meeting in the championship match on Sunday.

Some information for this report was provided by AP.