Wawrinka, Djokovic cruise past Berdych, Cilic on Day 2 at ATP Finals

LONDON -- It was one-way traffic at the O2 Arena on Monday, as No. 1 Novak Djokovic and No. 4 Stan Wawrinka lost just two games each en route to dominating wins

LONDON -- It was one-way traffic at the O2 Arena on Monday, as No. 1 Novak Djokovic and No. 4 Stan Wawrinka lost just two games each en route to dominating wins at the ATP World Tour Finals. Wawrinka came into the ATP World Tour Finals having won just one match since the U.S. Open but proceeded to put together the most dominant performance the tournament has seen since its move to London, beating No. 7 Tomas Berdych 6-1, 6-1 in less than an hour. Well, it was the most dominant performance until Djokovic matched his feat later in the evening, beating No. 9 Marin Cilic 6-1, 6-1.

ATP World Tour Finals Elite Eight talk tennis, family and the 2014 season

Djokovic needed just 56 minutes to dispatch of Cilic, who had not played a tournament since winning the Kremlin Cup three weeks ago. After winning the tournament, Cilic withdrew from the BNP Paribas Masters citing an arm injury. Prior to the tournament he said the injury was not 100 percent healed but it was good enough to play. In his ATP Finals debut, Cilic couldn't find the firepower and angles to hit through Djokovic. He struggled with his rhythm off the ground, hitting just six winners to 22 unforced errors. Djokovic, the two-time defending champion, hit 13 winners to 12 unforced errors. 

The more surprising result came earlier in the day when Wawrinka routed Berdych easily in just 58 minutes. He fired 16 winners to 11 unforced errors, while Berdych struggled to find his game. He won his second title of the year in Stockholm and made the semifinals of the Paris Masters two weeks ago. Though Wawrinka led their head-to-head 9-5 and had won their last four matches, Berdych was by far the more in-form player. Playing in his fifth ATP Finals, Berdych has now lost all five of his first round matches at the tournament. He called today's match his worst match of the season.

Roger Federer, Kei Nishikori lead Group B after Day 1 at ATP Finals

"I'm in the worst possible situation that I can ever be," Berdych said. Losing in straight sets is bad enough for his chance to qualify for the semifinals, but because one of the tiebreaking schemes is percentage of games won, winning just two games will almost surely put him at the bottom of the table after Day 2. "I'm going to face Marin or Novak first, in the end playing both of them, and the only chance to qualify is to beat them," he said. "It's almost a mission impossible."

Group A resumes on Wednesday when Djokovic plays Wawrinka and Cilic plays plays Berdych. 

Group B retakes the court on Tuesday with a blockbuster match between Roger Federer and Kei Nishikori as the headline in the afternoon session, at 9 a.m. ET. The two have split their four career matches, as well as their two matches this year, and the winner will take control of the group. Milos Raonic and Andy Murray will play in the evening session, at 3 p.m. ET. Raonic leads the head-to-head 3-1 and has never lost to Murray in a best-of-three match.