(Reuters) - For 15 minutes Novak Djokovic appeared to have a fight on his hands at the ATP World Tour Finals on Wednesday, then the Serb dialed up his A game and tore Stanislas Wawrinka to pieces.
Such was the perfection of his tennis for most of a 6-3 6-0 thrashing it is hard to argue against him crowning his year as world number one and with a hat-trick of titles at the ATP's year-ending showpiece.
The 27-year-old has conceded only five games so far at the cavernous O2 Arena yet the arithmetic of round-robin tennis means the seven-times grand slam champion is still not definitely assured of a semi-final spot.
Even more bizarrely, U.S. Open champion Marin Cilic, crushed 6-3 6-1 by Czech Tomas Berdych in the day's earlier Group A match could conceivably scrape through despite two heavy losses.
Just like his tennis Djokovic, who faces Berdych on Friday, cut straight through a question about whether or not he gets bogged down with the various scenarios.
"Nobody needs to tell me I need to win," he said. "That's what I try to do. That's why I'm here. I try to win every match I play on. That's the kind of approach I will have on Friday."
In actual fact Djokovic would go through to the semi-finals with a three-set defeat against Berdych who at least gave himself some hope by trouncing Cilic.
"I'm going to try to maybe win three, four games. That would be better than the last time," a smiling Berdych, beaten 6-2 6-0 by Djokovic in the recent Beijing final, told reporters.
Djokovic has played some epic matches against Swiss Wawrinka, most notably at the previous two Australian Opens, beating him in five in 2013 and then losing a fifth-set decider 9-7 this year in the quarter-finals.
World number four Wawrinka has been up and down since winning his first grand slam title in Melbourne, but he was flying at the start on Wednesday.
Striking the ball with ferocious power he broke Djokovic's opening service game and then held for a 2-0 lead.
The backlash was lethal, however.
Djokovic began exploring the corners with his surgical groundstrokes and Wawrinka was overwhelmed as he lost 20 out of 23 points in a five-game swing that snatched the match away.
Wawrinka held serve at 2-5 but Djokovic took the opening set in the next game and romped through the second set in 24 minutes, ending it when he drove a forehand down the line.
"I thought he played very well the first two games. But I wasn't frustrated. I kept my calm. After that, it was a really amazing performance," Djokovic said of his 29th consecutive indoor win that leaves him one victory away from sealing the year-end world number one ranking.
With eight matches down and seven remaining, the sell-out O2 crowds are yet to see a singles match go the distance.
"It's the tournament of the best eight players in the world, people, fans, the crowd expect to see a little bit more excitement and longer matches," Djokovic said.
"I think that's going to change as the tournament progresses."
Berdych's defeat of Cilic was equally emphatic, although the Croatian debutant looks spent, having managed six games so far.
Cilic never looked comfortable from the moment he dropped serve in the first game and although he did have two break points to get back to 4-4 in the first set, Berdych held firm and went on to dominate the rest of the match.
It was quite a rebound for Berdych who had said he faced "mission impossible" after an opening 6-1 6-1 loss to Wawrinka.
"I think that's the beauty of this event," he said. "One day you can be swept from the court like I was and in two days' time you can come up play different tennis."
American world number one doubles duo Mike and Bob Bryan also got back to winning ways as they came from a set down to beat Jean-Julien Roger and Horia Tecau.
