Novak Djokovic moved within touching distance of ending the year as the world number one after crushing Stan Wawrinka 6-3, 6-0 at the ATP Tour Finals on Wednesday.
Djokovic needs to win all three of his Group A matches to ensure he will hold off Roger Federer in the race for first place and the Serb secured the second of those victories with a ruthless 65-minute rout at London's O2 Arena.
The reigning Wimbledon champion will be guaranteed top spot if he beats Tomas Berdych on Friday in a match he also has to win to be certain of making the last four at the prestigious season-ending event.
Wawrinka's loss means the Swiss world number four needs to defeat US Open winner Marin Cilic, thrashed 6-3, 6-1 by Berdych earlier on Wednesday, to have a chance of making the last four.
After demolishing Cilic for the loss of two games on Monday, Djokovic has lost only five games during his first two matches.
Djokovic has won his last 29 indoor matches, including 12 in a row at the Tour Finals, and he remains on course to become the first player since Ivan Lendl in the 1980s to win the Tour Finals three years in a row.
"It was a great match, no question. The opening three games were quite long but after that I managed to get back in the first set," Djokovic said.
"I swung through my shots and he made a lot of unforced errors. He wasn't close to his best and I succeeded very well with what I wanted to do."
Berdych's win over Cilic meant Djokovic was unable to guarantee his place in the last four whatever his result, unlike Wawrinka, who started knowing a victory would send him into the last four with a match to spare.
But Djokovic had dominated his head to head match-up with Wawrinka, winning 15 of their 18 meetings.
With a semi-final place up for grabs, Wawrinka came out swinging and he landed an early blow with a break in the first game.
But Djokovic is far too cool a customer to be rattled by that opening salvo and he broke back in the fourth game.
That was the signal for Djokovic to step up a gear and he took 21 points from a possible 24 during a run of five successive games that brought him a 5-2 lead.
Wawrinka finally halted Djokovic's streak in the next game, but it was too late to save the set.
There was no let-up from the Serb in the second set and he continued to overwhelm Wawrinka from the baseline as he broke in the first game.
That shattered Wawrinka's resolve and the Swiss was blown away as took 12 of the final 13 games to leave his shell-shocked opponent shaking his head in disbelief as winner after winner flashed past him.
Djokovic's stroll continued a trend that has seen all eight singles matches won in straight sets with little drama to entertain the 17,500 capacity crowds.
Berdych had been routed by Wawrinka in his opening match, but the Czech bounced back in style against Cilic and can still make the last four.
"It's not my first year. I have the experience of losing the first match in the past and I know how to come back. I think that was the biggest difference," Berdych said.
Quizzed during an on-court interview about the daunting task of facing Djokovic, Berdych jokingly asked the crowd: "Any tips? I will need some.
"I just want to try to bring my best tennis and we'll see what happens."
Cilic's second straight-sets defeat at the season-ending event means the Croatian has no chance of qualifying after winning just six games in his two matches.
"It's disappointing to play like this. I was not expecting it. But my body feels a little bit tired on the court," Cilic said.