Andy Murray says No 1 ranking has not changed him after ATP World Tour Finals win

Andy Murray said becoming world No 1 has not changed his mentality after beating Marin Cilic in his first match as the best player on the planet.

The 29-year-old Scot overcame an unsettled start to win 6-3 6-2 in his opening round-robin tie at the ATP World Tour Finals in London.

He had to save two break points in the first game and then dropped his serve in the third, but he insisted his early struggles were more down to the conditions in the O2 Arena than nerves.

Murray wins debut as No 1

Andy Murray claimed his 20th win in a row by beating Marin Cilic in straight sets

Speaking at his post-match press conference, he said: "I haven't thought about it [becoming world No 1] too much. It didn't change much for me.

"I didn't feel any more nervous than usual. It's just quite different conditions in there than what we have been practicing in during the week. It's a lot slower than it has been.

"Obviously, playing with a packed crowd, it changes things a bit. I think maybe some of the errors at the beginning were more getting used to playing in new surroundings again."

Murray has now won 20 games in succession and __can make it 21 when he faces Kei Nishikori on Wednesday in his second round-robin match.

Nishikori was in blistering form when beating Stan Wawrinka 6-2 6-3 earlier on Monday and is likely to present Murray with a far sterner challenge than the misfiring Cilic did.

Murray added: "I didn't see the match, but he obviously must have played very well. To win against a player like Stan with that scoreline, I don't think Stan had really any chances on Kei's serve either.

"I would say this is probably his best year that he has had on the tour.

"He is one of the best players in the world. He has been playing very well the last few months especially."

Watch every day of the ATP World Tour Finals, from November 13-20, live on Sky Sports. Full schedule here.

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