Novak Djokovic has won his 30th successive match, beating Kevin Anderson of South Africa 6-3, 6-4 to reach the third round of the Madrid Open.

Djokovic's winning streak dates to Serbia's win in the Davis Cup final last December. This year, he's started 28-0, the best start to a season since Ivan Lendl went 29-0 in 1989.

In the next round, Djokovic will play Guillermo Garcia-Lopez of Spain, who has yet to beat the Serb after four meetings.

Third-seeded Tomas Berdych and fifth-seeded Robin Soderling were also winners.

On the women's side, Petra Kvitova of the Czech Republic eased past second-seeded Vera Zvonareva 6-1, 6-4 to reach the quarterfinals.

On Tuesday, in-form Spaniard David Ferrer survived a tough opening match at the Madrid Open when he dropped the second set to French qualifier Adrian Mannarino before winning 7-5, 0-6, 6-0 in the second round.

Ferrer, seeded six for the clay event in the Spanish capital and runner-up to world No. 1 and compatriot Rafa Nadal at last month's Monte Carlo Masters and Barcelona Open, will play Sergiy Stakhovsky for a place in the last 16.

Ukrainian Stakhovsky edged past big-serving American John Isner 7-5, 4-6, 7-6 earlier on Tuesday in a match featuring only one break of serve for each player.

Former world No. 4 Juan Martin Del Potro continued his comeback from a wrist injury with a 6-1, 3-6, 6-3 first-round victory over Russia's Mikhail Youzhny, the 13th seed, at the futuristic Magic Box arena.

Fifteenth seed Fernando Verdasco, another Spaniard, was upset 6-7, 5-7 by unseeded Lu Yen-Hsun of Chinese Taipei, while local wildcard Marcel Granollers eliminated Russia's Nikolay Davydenko 7-5, 6-2.

France's Gilles Simon won a tight match against Croatian Ivan Ljubicic 7-5, 7-6 to set up a second-round meeting on with fourth-seeded Briton Andy Murray. Nadal, who was given the usual bye into the second round for the top eight seeds, opens his campaign against former Australian Open finalist Marcos Baghdatis.