Djokovic, seeded third, didn't face a break point in taking a 6-3, 6-3 victory in the first match of the Group A round robin. World No. 1 Rafael Nadal was to meet eighth-seeded Andy Roddick later Monday in another Group A match.

Djokovic won a healthy 72 percent of the points on serve in beating the sixth-seeded Berdych. He was able to cash in three of seven break points he forced on Berdych, including one in the opening game of the match.

Berdych had two double faults in that first game and had to save four break points in the third game to avoid falling down two breaks.

Djokovic also broke Berdych's serve in the second game of the second set to establish control of the match.

No. 2-seeded Roger Federer and fifth-seeded Andy Murray claimed first-day wins Sunday to take the early advantage in Group B, which has its second set of matches Tuesday.

The top two players in each group advance to the tournament semifinals Saturday.

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