Zverev keeps calm to beat Cilic after two tie-breaks

"I just knew this is a very important match, you don't want to start the group stages with a loss".

The 29-year-old Pole, who reached a career-high ranking of No. 2, says she is "no longer able to train and play the way I used to".

He has two wins and is yet to drop a set.

Several leading players, including Djokovic, have questioned the timing of the ITF's flagship event, coming at the end of a gruelling 11-month season and Germany's Alexander Zverev said this week he would not play in the showpiece finals.

"The win, that's the most important thing", said Zverev, who failed to advance from the round-robin stage on his debut previous year.

Zverev nailed a backhand victor down the line to earn five more match points and converted the first with a powerful first serve that Cilic fenced into the net.

His victory means the day's second singles between group victor Novak Djokovic and Marin Cilic is academic - apart from ranking points and the $200,000 on offer for each round-robin win at the year-ending showpiece. That allowed me to step in.

"I am going to enjoy some quality time with my family and then get ready for the last game in the group".

Zverev is emerging as one of the Tour's brightest young stars after climbing to fifth in the world and reaching the French Open quarterfinals this year. With Cilic serving for the set at 5-3, Zverev broke back before holding serve with an ace to level at 5-5.

While the O2 Arena has been a happy hunting ground for Djokovic with four of his five ATP Finals titles arriving there, the same can not be said of four-time qualifier Cilic.

Despite his hopes having gone, Isner stuck to his task in the second set but Zverev, still needing the victory to make sure of his semi-final berth, powered to his 56th win of the year.

It seemed to knock the stuffing out of Zverev, who was broken in the fourth game of the second set, and again to love in the sixth. "He made a lot of unforced errors which helped me to win".

Kevin Anderson tops the Lleyton Hewitt Group with two victories, four sets without conceding one, for a tally of 25 games won and 10 lost.

Djokovic said: "It's great to be back in the 02, it's been a lucky place for me over the years".

Cilic's revival keeps him in with a chance of qualifying for the semi-finals, while American eighth seed Isner still has an outside chance of advancing despite losing his first two matches.

  • Stacy Allen