Davis Cup captain John Lloyd today challenged Andy Murray to give the British team a boost by seeing off Jurgen Melzer when they clash here in the third round of the US Open.

Melzer is due to spearhead the Austrian opposition in a World Group relegations play-off at Wimbledon next month and a resounding win by Murray in New York will give his team-mates a huge tonic.

Murray, brother Jamie, doubles expert Ross Hutchins and Alex Bogdanovic, the other singles player, have the difficult task of keeping Britain among the elite of 16 nations.

The British No1, whose sights are set on reaching his first Grand Slam semi-final, survived a difficult second-round battle with French world No38 Michael Llodra. He emerged a satisfied 6-4, 1-6, 7-5, 7-6 winner but the match saw his temper tested to the limit.

Murray constantly argued with the umpire over line calls and ended one frustrating game with a loud torrent of words, which were difficult to hear because he sensibly covered his mouth with his hand. That saved him from any warnings from the umpire.

In previous years, such an emotional outburst may have cost him victory. But the world No6 is maturing on the big stage and his Cup captain is impressed.

Lloyd said: "Andy has a great shot a reaching the semi-finals for the first time and that's very possible if he comes up against someone like Spain's David Ferrer in the last eight. It's a great opportunity, even though the matches will be tough, and, overall, it's a good draw for him.

"It would be great if Andy could beat Melzer here. I would like that a lot because Melzer is a very good player.

"There will be a lot of pressure on Andy, particularly in that Cup tie, and dealing with that is what top 10 players have to do. We are slight favourites on grass against Austria."

Murray is refusing to look any further ahead than the match with Melzer, a player he defeated in three sets earlier this year at Indian Wells.

He said: "One win doesn't make me start looking into the semis and quarter-finals, because I only have made the last eight of a Slam once. I am not good enough to be able to do that."

Murray is a fan of the Hawkeye line calling system and will be hoping his next match is on a court where it operates and not the Grandstand arena where he beat Llodra.

He said: "If there are calls like that when it's one of the biggest tournaments in the world, then it isn't nice to have that sort of lack of confidence in a lines judge or in the umpire.

"I thought I hit the ball from the back of the court very well and I didn't feel like I was making many mistakes from the baseline. There weren't too many unforced errors and for a huge part of the match it was very tricky for me to serve from the end where the tough calls were coming and I was happy I won in four sets.

"Melzer is another lefty who comes to the net a lot, plays aggressively and is a tough guy to play against. He doesn't give you too much rhythm but I feel I am playing well and I am looking forward to the match."

If Murray does reach the semis he is likely to face world No1 Rafael Nadal, who had little trouble beating American qualifier Ryler deHeart. The Spaniard eased into the third round with a 6-1, 6-2, 6-4 victory.

Jamie Murray, meanwhile, still believes he will partner Max Mirnyi in the men's doubles next year despite another disappointing Grand Slam showing. The 14th seeds lost their first round match to Michael Mertinak and Lovro Zovko 7-6, 7-6.