LONDON: Dominic Thiem showed more of his clutch tennis on Tuesday at the Barclays ATP World Tour Finals in London.

The Austrian kept alive his semifinal hopes by beating Gael Monfils 6-3, 1-6, 6-4 in their Group Ivan Lendl match. The 23-year-old debutant broke Monfils at 5-4 in the third set to earn his first victory at the season-ending championships.

“I had a good start today. I was trying to stay tough in the third set but at the end, of course, he helped me a little bit with the three double faults. But I’m very happy with the win,” said Thiem. “This tournament, the big crowd, gives me and probably all the players a lot of energy.”

Thiem also improved his record in deciding sets this season to 22-3, which leads the ATP World Tour. He now leads his FedEx ATP Head2Head rivalry with Monfils 2-0. The right-hander started the match on a roll, much like he did on Sunday against Novak Djokovic. Thiem won almost 90 per cent of his first-serve points (17/19) and never faced a break point in the first set against Monfils, who’s also making his London debut and was going for his first win at The O2. Monfils fell to Canadian Milos Raonic on Sunday.

Monfils marched back in the second set, breaking Thiem three times to win his first set in London and even the contest. But Thiem, as he’s been all season long, was more solid in the match’s tightest moments. Monfils floated a backhand long on match point to fall to 0-2 in London.

In a night match Monday, Andy Murray celebrated his rise to the top of the world rankings with a 6-3, 6-2 victory over Marin Cilic, as the Scot made a strong start to his bid to win the ATP Tour Finals.

Murray was officially confirmed as the first Briton to reach number one last Monday and he marked his first match since that historic moment by dispatching Cilic at the prestigious season-ending event at London’s O2 Arena.

The 29-year-old took only 90 minutes to extend his remarkable winning streak to 20 matches as he looks to add to the four consecutive titles he won in Beijing, Shanghai, Vienna and Paris.

It was exactly the start Murray needed because to guarantee ending 2016 in pole position, he must win the Tour Finals title for the first time, with anything less than that giving Novak Djokovic the chance to overhaul him depending on the deposed number one's own results.

"It's a great atmosphere and I think I played one of my best matches here. I'm going to keep working hard to give people moments like this," Murray said.

"I have confidence from winning matches and I was a little bit more solid when I had opportunities."

Murray has enjoyed an incredible 11 months in which he has won Wimbledon for the second time, claimed a second Olympic singles gold medal and become a father for the first time.

So it was fitting that Murray's first appearance as the world's best player came within an hour's drive of his family home in Surrey.

While Murray has amassed a combined seven titles across London at Wimbledon and Queen's, he has failed to reach the final of the Tour Finals in six attempts and this was one of his better displays at the O2.