Dubai, United Arab Emirates (SportsNetwork.com) - Novak Djokovic was an easy winner Tuesday in the first round of the Dubai Tennis Championships, but Juan Martin del Potro was forced to withdraw from his opening match because of a wrist injury.

The top-seeded Djokovic is the defending champion and a four-time winner of this event. In addition to last year's victory over Tomas Berdych in the final, the Serb also won this title from 2009-11.

"The atmosphere is great. I enjoy it," said Djokovic. "It's a beautiful stadium. I have had lots of success on this court, at this tournament, and I always look forward to coming back."

On Tuesday, the former world No. 1 posted a 6-3, 6-3 win over Uzbekistan's Denis Istomin. He'll next face Spain's Roberto Bautista Agut, who won his first-round match on Monday.

The second-seeded del Potro decided to call it quits after dropping the first set of his match against India's Somdev Devvarman in a tiebreaker. Devvarman will next play fellow wild card Malek Jaziri, as the native of Tunisia rallied after a disastrous first set to claim an 0-6, 6-4, 7-6 (7-4) win over Dutchman Igor Sijsling.

Berdych, this year's third seed, also eased into the second round with a 6-3, 6-4 win over Romanian qualifier Marius Copil, while Frenchman Jo-Wilfried Tsonga and Russian Mikhail Youzhny were other seeded winners Tuesday.

The fifth-seeded Tsonga had little trouble in a 6-2, 6-4 win over Romania's Victor Hanescu, while the sixth-seeded Youzhny earned a 6-3, 6-4 triumph over Poland's Michal Przysiezny.

Next up for Berdych will be the Ukraine's Sergiy Stakhovsky, who gutted out a 7-6 (8-6), 6-7 (4-7), 6-2 win over Croatia's Ivan Dodig. Tsonga will next meet Russian veteran Nikolay Davydenko, a 7-6 (8-6), 6-4 winner over Kazakhstan's Andrey Golubev, while British wild card James Ward will next take on Youzhny after rallying for a three-set triumph over Russia's Teymuraz Gabashvili.

Czech natives Lukas Rosol and Radek Stepanek also won Tuesday. Rosol topped Germany's Daniel Brands in straight sets, while Stepanek moved on with a 5-7, 6-3, 6-1 win over American Michael Russell and will face fourth-seeded Roger Federer in the second round.

Federer, a five-time Dubai winner, won his first-round match Monday.

Since 2003, Djokovic and Federer have won nine of 11 titles in Dubai.