In Andy Roddick’s words, he and Novak Djokovic have been through it “a million” times – the pressure, the occasion and the formidable opponent. The Olympics, though, bring an unusual twist. Roddick, a three-time Wimbledon finalist, and Djokovic, the 2011 champion at the All England Club, will today play in the second round of the Olympics. Both are wary of each other’s weapons, and both embrace a sporting spirit that transcends individual achievement. “Ninety-five percent of the time, when a tennis player plays, it’s for pretty selfish motives, and this week is not one of those,” Roddick said yesterday after defeating Martin Klizan of Slovakia, 7-5, 6-4. “So it is a different dynamic here.” Serena Williams beat Urszula Radwanska of Poland, 6-2, 6-3 in the second round on Court 1, just weeks after defeating Radwanska’s sister, Agnieszka, in the Wimbledon final this month. Tomorrow, the five-time Wimbledon champion plays No. 13-seeded Vera Zvonareva, the Russian she beat in 2010 for the fourth of those titles. Top-seeded Roger Federer made a brief appearance on Centre Court, beating Julien Benneteau of France 6-2, 6-2 in less than an hour to reach the third round.

Second-seeded Djokovic, who lost to Federer in the semifinals at Wimbledon, would seem to have the edge over Roddick, whose world ranking has slipped to 22. The Serb was not complacent. “Andy has one of the strongest serves in the world, ever, and it’s his biggest weapon,” Djokovic said. “The grass courts this year are very fast and it’s a low bounce, so I think I will have to be on top of my game in order to win that match.” Even as he prepared for the contest, Djokovic relished the “special feeling” of being part of something larger, a team that represents his country.

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