Andy Ram and Max Mirnyi took a significant step towards advancing to the semifinals of the ATP World Tour Finals in London, England, on Monday, defeating number 2 seeds, Bob and Mike Bryan, 6-4, 6-4 in the doubles tournament opener. Despite the convincing straight-sets victory, Ram will not be getting ahead of himself just yet. The Israeli also won his first round robin match in his two previous appearances in the prestigious season-ending tournament only to eventually miss out on a semifinal berth. His showings in what was then known as the Masters Cup came in 2006 and 2007 with regular partner Yoni Erlich. Superb serving was the key to the Israeli/Belarusian duo's impressive victory on Monday. Ram and Mirnyi got 78 percent of their first serves in and subsequently won 33 of 38 points. "Be aggressive, play with energy," Ram answered when asked of the team's tactics in Monday's victory. "The Bryans always play with high energy. You have to keep up the same intensity. "We did that well today. We have to serve very well against the Bryans and stay all the time ahead, if you can. When they're ahead, it's tough to catch up." Despite being broken in the second game of the match, Ram and Mirnyi fought right back and reeled off the next four games. The duo trailed 0-30 when serving for the set in the 10th game, but didn't give the Americans a chance to break back and a Ram smash clinched the first set. Ram and Mirnyi began the second set with a break and never looked back. The Bryans failed to reach a single break point in the second set and a Mirnyi ace wrapped up the win. "Today was a good day for us," said Mirnyi. "We did what we wanted to do and managed to execute the game plan we had. So when that happens, it's a good indication for our game. "We're here to play our best tennis," the 32-year-old righthander added. "In the round-robin format, we know we're going to be in for three matches, and we want to make sure we do our best each point at a time, each game at a time, and see what happens at the end of the round robin. "We certainly are happy, excited, confident about playing this tournament, and look forward to winning every match we can play." Meanwhile, Rafael Nadal lost to Robin Soderling for the second straight time on Monday, falling 6-4, 6-4 in their opening round-robin match of the singles tournament. Soderling, who handed the Spaniard his first ever loss at the French Open this year, powered his way through the Group B match by mixing a hard forehand with a solid backhand to keep Nadal on the move. The second-ranked Nadal can still advance to the semifinals of the season-ending tournament for the top eight players in the world. Novak Djokovic was to play Nikolay Davydenko later Monday in the other Group B match. Late Sunday, Roger Federer overcame an erratic forehand and Fernando Verdasco, rallying to beat his Spanish opponent 4-6, 7-5, 6-1. The top-ranked Federer was broken only once - in the opening game of the Group A match after double-faulting on the first point - but he never looked dominating until late in the second set when he converted his first break point to even the score at one set apiece. In the third set at the O2 Arena, Federer was back to his old self. He controlled play as usual, and gave Verdasco little chance to stay in the match. "I was down a set, and only the second set was I able to sort of get the ball into play, find my range, find my rhythm," Federer said. "This is also when I started to feel like I had chances. "My first break points, I think I could have had them earlier if I played a bit earlier, but they came for set points, and it was a crucial moment for me because I knew the longer the match went, the more my belief was going up and his was going down. Then in the third, I was able to play more freely." AP contributed to this report.