Andy Murray has heeded caution ahead the start of his US Open defence against Frenchman Michael Llodra at Flushing Meadows.

The Wimbledon champion takes on the world No.49 on Wednesday in a belated start to his title defence.

Murray has a 3-0 win record over the 33 year old, the most recent of which came at the Australian Open in 2012 which saw the Brit drop just six games.

But the two-time major winner says it will be no plain sailing in round one against the dangerous Llodra.

"The conditions here obviously can change a lot from day to day," said Murray. "When it's warm here it's pretty quick, probably the quickest of the Slams.

"When it's cool in the evening, it slows down significantly, so I'll have to wait and see.

"It's a tough match. Llodra is tricky player, serves well, one of the best doubles player in the world just now, very good hands, and he's very unpredictable.

"You need to be switched on all the time against him and play a solid match. You can't have too many ups and downs against him because he will capitalise on that."

"I think there is less pressure," Murray added. "I think before the first match there will be nerves there - I expect to be pretty nervous because it's a new experience and it's different - but I think once the tournament gets going, I don't think it changes too much.

"There was a lot of pressure on me for a lot of years to win a Grand Slam, and then the same sort of thing at Wimbledon. I wouldn't imagine it would be the same here."

Murray will be hoping to sustain British success in the opening week in New York after both Dan Evans and Laura Robson made it into round two after wins over Kei Nishikori and Lourdes Dominguez while Heather Watson starts her campaign on Tuesday against Simona Halep.