Dudi Sela climbed to a career best number 33 in the world on Monday morning and hours later continued to familiarize himself with the Nokia Arena ahead of this weekend's Davis Cup quarterfinal tie against Russia. The 24-year-old jumped 13 places in the ATP rankings after reaching the fourth round at Wimbledon last week, his best achievement ever in a Grand Slam tournament. "This is one of the happiest days of my life," Sela said of entering the world's top-40 for the first time in his career. "This is the reward for all the hard work I've put in and I hope it will also show against Russia over the weekend." Sela has won seven of his last eight matches in the Davis Cup and is hoping once more to lead the team to an historic triumph. "We hope we can surprise the Russians," Sela said. "We are a united team and each of our players can bring the team the points it needs." Andy Ram and Yoni Erlich, who have barely teamed-up in the past 10 months, continued to train together on Monday. "I'm excited to be playing with Ram again," said Erlich, who returned from an eight-month injury layoff a couple of months ago. "I'm feeling excellent and I got back into shape very quickly." Meanwhile, Roger Federer is back at No. 1. Federer returned to the top of the ATP rankings Monday, a day after winning Wimbledon by edging Andy Roddick 16-14 in the longest fifth set in Grand Slam final history. Federer moves up from No. 2, switching places with former No. 1 Rafael Nadal. "It's fantastic, because definitely, when you lose No. 1, you never know if you're ever going to return to it," Federer said Monday at the All England Club. "I always thought it was easier staying No. 1 than getting there." A year ago at Wimbledon, Nadal beat Federer in the final and overtook him atop the rankings in August. That ended Federer's record stay of 237 consecutive weeks at No. 1, a streak that began on Feb. 2, 2004, after his first Australian Open title. "Once I was No. 1, everything just clicked, and everything was easy," Federer said. "I beat all the other top-10 guys, I won every final I played, and so I hope that's going to return again, that I'm able also to dominate my fellow rivals again and go from there. I'm delighted, of course, I'm No. 1 again." Nadal did not defend his Wimbledon title, citing sore knees. His lead over Federer had taken a big hit when Nadal lost in the fourth round at the French Open this year, after having won that major title four consecutive years. Sunday's title was Federer's sixth at Wimbledon and record-breaking 15th major overall. The rest of the men's top 10 was mostly unchanged, with Roddick remaining at No. 6. Dinara Safina kept her hold on No. 1 in the WTA rankings, ahead of Wimbledon champion Serena Williams, who stayed at No. 2, and runner-up Venus Williams, still No. 3. Serena beat Venus in straight sets Saturday for her third Wimbledon title and 11th career major championship. Serena has won three of the past four Grand Slam titles. Safina, meanwhile, was beaten 6-1, 6-0 by Venus in the semifinals at the All England Club - the most lopsided loss ever by a reigning No. 1 woman. Safina - No. 1 since April - hasn't won a Grand Slam title, going 0-3 in major finals. "I'd rather definitely be No. 2 and hold three Grand Slams in the past year than be No. 1 and not have any," Serena said Saturday.