Updated

Wimbledon champion Roger Federer secured a berth in the quarterfinals at the London Olympics tennis event.

The world No. 1 Federer was tested in the first set en route to a 7-5, 6-3 third-round victory over Uzbekistan's Denis Istomin on Court 1 at the All England Club, where the Swiss icon has captured seven Wimbledon championships, including his most-recent one only four weeks ago. The match was interrupted by rain, with the score tied at 5-all in the first set.

Federer moved on in 81 minutes despite committing an uncharacteristic 24 unforced errors over two sets. The Swiss great, however, was broken only once en route to victory.

The 30-year-old Federer's quarterfinal opponent will be seventh-seeded Serb Janko Tipsarevic or 10th-seeded American John Isner.

Federer would complete a career "Golden Slam" with a gold-medal performance this week.

Meanwhile, eighth-seeded Argentine slugger Juan Martin del Potro defeated 12th-seeded Frenchman Gilles Simon 6-1, 4-6, 6-3 and 11th-seeded Spaniard Nicolas Almagro handled Belgian Steve Darcis 7-5, 6-3. Del Potro captured a U.S. Open title in 2009 by stunning Federer in the final in New York.