DELRAY BEACH, Fla. — Second-seeded Mardy Fish defeated Ricardo Mello 6-2, 6-1 in a matchup of former champions in the second round of the Delray Beach International Tennis Championships on Thursday.

DELRAY BEACH, Fla. — Second-seeded Mardy Fish defeated Ricardo Mello 6-2, 6-1 in a matchup of former champions in the second round of the Delray Beach International Tennis Championships on Thursday.

Fish broke Mello's serve in the first and fifth games of the first set and only allowed the Brazilian to hold serve in the opening game of the second.

The American advanced to the quarterfinals where he will play qualifier Alejandro Falla, who beat Adrian Mannarino 6-3, 6-2.

Juan Martin del Potro beat Teymuraz Gabashvili 6-1, 6-1.

Del Potro never offered Gabashvili a break point opportunity in the match. Gabashvili held serve twice; in the fifth game of the first set and second game of the second set.

Del Potro will play fifth-seeded Kevin Anderson of South Africa in the quarterfinals. Anderson easily defeated Florent Serra of France 6-1 6-4.

The other quarterfinals feature sixth-seeded Janko Tipsarevic of Serbia against Ivan Dodig of Croatia, and 2008 Delray Beach champion Kei Nishikori against qualifier Ryan Sweeting.

Dubai Championships

At Dubai, United Arab Emirates, Roger Federer and Novak Djokovic, winners of six of the last eight Dubai Championships, remained on course to play for the title by winning quarterfinal matches in straight sets.

Federer was broken for the first time in three matches but defeated Sergiy Stakhovsky of Ukraine 6-3, 6-4. Novak Djokovic beat Florian Mayer of Germany 7-5, 6-4.

Federer will play Richard Gasquet, who downed Gilles Simon 5-7, 6-2, 6-4. Djokovic will play Tomas Berdych in a rematch of their Australian Open quarterfinal.

Next up for Djokovic is Berdych, who beat big-serving Phillip Petzschner of Germany 7-5, 6-4.

Qatar Ladies Open

At Doha, Qatar, Vera Zvonareva rallied from 5-3 down in the deciding set to defeat Daniela Hantuchova 7-5, 6-7 (5), 7-5 in a quarterfinals match.

Zvonareva reached a semifinal against familiar foe Jelena Jankovic, who defeated Klara Zakopalova of the Czech Republic 6-2, 6-4. Top-ranked Caroline Wozniacki beat Flavia Pennetta of Italy 6-2, 6-0 and set up a semifinal with Marion Bartoli, who defeated Peng Shuai 6-2, 6-2 in 71 minutes.