ANDY MURRAY takes on Croatia's Ivan Ljubicic in the quarter-finals of the BNP Paribas Open in Indian Wells today after fourth-round opponent Tommy Robredo retired with an injury.

The Spaniard called a halt to proceedings complaining of trouble with a wrist in the second set, with Murray 6-2, 3-0 up.

In sweltering conditions, Murray continued to make an encouraging recovery from the virus which kept him out of Great Britain's Davis Cup tie with Ukraine, punishing a host of unforced errors from Robredo and coming up with a pleasing range of groundstrokes.

Robredo, who had won both of the pair's previous two meetings, started confidently and broke Murray in the third game when the Scot double-faulted.

But Murray imme- diately responded, breaking back to love, holding his serve and then breaking Robredo again in the sixth after saving game point with a superb rally.

The world No.4 said he was surprised to see his opponent retire given the power in his shots during the encounter.

"I'd seen him before the match having ice on his wrist but he was hitting the ball well, serving big and I didn't see him letting up on too many shots. But obviously it was affecting him," Murray said.

The Dunblane ace was pleased with his movement but said there were still aspects to his game that he was looking to polish as the competition progresses.

He added: "I'd like to hit the ball a little bit cleaner from the back and the start of all my matches have been a little bit passive while I've been trying to work my way into a rhythm.

"I went behind early against (Albert) Montanes and again against Robredo and I'll try and cut that out."

The fourth seed admitted that he could now go on to win the tournament but said: "The conditions are tough, it's really hot out here and Ljubicic plays well around the net in these conditions. He has got a huge serve.

"So I think I've got a chance of winning the tournament, but I'm still looking ahead to the Miami Masters."