Andy Murray: I'll ignore noise to focus on World Tour glory

The Scot's opening round-robin clash at London's O2 Arena is against Croatian Marin Cilic.

The format theoretically allows players more breathing space but Murray cannot afford any slip-ups if he is to avoid giving Novak Djokovic top spot back after only a fortnight.

The Serbian began his campaign on Sunday with a 6-7 (10/12) 6-0 6-2 victory over Dominic Thiem to keep the pressure on.

Murray must out-perform his rival to be sure of staying ahead, and history suggests that will not be easy.

While Djokovic has won the title the last four years, losing just one round-robin match, Murray has not reached the semi-finals since 2012 and has never gone further.

The draw was also not kind, with Murray's group of Cilic, Stan Wawrinka and Kei Nishikori certainly significantly tougher on paper than Djokovic's line-up of Milos Raonic, Gael Monfils and Thiem.

No surprise, then, that Murray will be trying to put all ranking scenarios firmly out of his mind this week.

He said: "It's an incredible feeling to have made to world number one, and it's something I'm very proud to have achieved.

"It's important to keep taking it one game at a time to try and perform as best you can during each match and try to ignore the noise around you.

"(Number one) came earlier than I first anticipated after a hectic few months, which is great, but now it's important that it's business as usual. It will make for an exciting battle in London but also for next season."

Cilic is arguably the tour's form player behind Murray, having won a title in Basle last month and then ended a 14-match losing streak against Djokovic in Paris 10 days ago.

That enabled Murray to snatch the number one ranking, but Cilic is determined not to do his rival any more favours and could have a not-so-secret weapon in his coach Jonas Bjorkman, who was part of the Scot's team last year.

Cilic, who won his last meeting with Murray in Cincinnati in August, said: "When a coach works with a player always you get to know more things than when you're looking from the outside.

"Definitely having Jonas on my side now is a big plus. I'm going to be able to prepare a good plan for the match. But things are not always as you expect, you always need to find a way if things go wrong.

"I have to obviously focus on myself, on my game, and implement as well a few tactical things I know from playing Andy."

Milos Raonic was a winner on the opening day, beating Gael Monfils 6-3 6-4, while Jamie Murray and his Brazilian partner Bruno Soares defeated Treat Huey and Max Mirnyi 6-4 7-5 in the doubles.