Ivan Ljubicic has insisted that big-serving Ivo Karlovic can play without pressure when he takes on Andy Murray in the Wimbledon fourth round on Monday.

Karlovic has served 136 aces on the way to reaching the last 16, and even though he is the underdog against the third seed, Ljubicic, the former Croatian number one, believes that his compatriot will enjoy the occasion.

Ljubicic is quoted by Sportinglife.com as saying: "Ivo has absolutely nothing to lose. He is really relaxed. At 36, what he went through not only in his tennis but the health scare he had a couple of years ago, he is just enjoying it.

"Literally five minutes before his last match against Tsonga, we were joking in the locker room, he was so relaxed and said: 'I have nothing to worry about. I know what I know and I also know that I won't learn what I don't know'.

"He is completely aware of his strengths and weaknesses and he is just doing what he does the best: serving and attacking as much as he can. He is in heaven."

Karlovic is a former quarter-finalist at SW19, but has failed to see off Murray in any of their five previous meetings.