Stanislas Wawrinka kept alive hopes of reaching the semi-finals of the ATP World Tour Finals for a fourth straight year after defeating Marin Cilic in straight sets at The O2 Arena. The three-time grand slam champion took both sets via tie-breaks, with the result preventing Andy Murray from qualifying for the last four and ending the Croatian's campaign in London.

Though the 31-year-old was not at his very best, he improved sufficiently from his straight sets loss to Kei Nishikori to send Cilic packing ahead Croatia's Davis Cup final against Argentina. He won both breakers 7-3 as Cilic, who joins Gael Monfils in being knocked out of the tournament, wilted at the vital moments.

The result means three players in John McEnroe group can still qualify for the semi-finals, despite Murray winning his opening two matches over Cilic and Nishikori. Wawrinka will take on the world number one on Friday [16 November], while Nishikori takes on Cilic.

"It was about a few points," he said. "It was a tough match as it always is against Marin. It is never easy to play especially indoors. I am really happy with the way I was fighting. I think it was a great match. It is important as it is the last event of the year. It is an honour to play here and I am fighting as much as I can to win matches."

Wawrinka was protecting a record of having reached the semi-finals on each of his three previous appearances at the ATP Finals, while Cilic was looking for his first ever win in format, having lost four in a row. If the Croatian could claim what would be just a third ever win over Wawrinka then Murray would be assured of processing from the John McEnroe group without hitting another ball.

Chances to break were few and far between for both players in the opening exchanges as their services game dominated. Cilic was the first to threaten however in the form of a set point in game 10, but Wawrinka snuffed out the opportunity with a pincer-like body serve.

Such was the consistency of both players, a first set tie-break was inevitable. Wawrinka claimed the mini-break at the change-over after a Cilic error, and though the 6ft 6ins Croat saved one set point an overhead volley thundered the Swiss into the ascendency.

But the position of dominance was short-lived as Cilic broke in the opening game of the second set as Wawrinka went long on the backhand side. Any fear Wawrinka would quickly lose interest were eased when he broke back for 2-2, as Cilic failed to get back a potent forehand.

Opportunities to re-establish the lead were missed by Cilic when he chose delicacy over power and allowed Wawrinka off the hook. Cilic's frustration was building up and upon striking an errant backhand he threw his racquet to the ground in disgust.

The second set looked destined to go the same way of the first until Cilic came out to serve to stay in the match for a second time, with a forehand error and then a double fault twice putting Wawrinka within two points of victory. But Cilic wriggled away from danger to take the contest to a second tie-break.

Once again Wawrinka grabbed the mini break with a stinging forehand before two points on serve gave him three match points, the first of which he took to keep his hopes of reaching the knock-out phase and remaining at world number three, very much intact.