Andy Murray beat Roko Karanusic in straight sets to extend Great Britain’s Davis Cup lead over Croatia to 4-0 in the first dead rubber at the All England Club today.

Forced into action by an elbow injury which afflicted his brother Jamie, Murray triumphed 6-4, 7-6 to the delight of the Court No1 crowd, who might normally have expected to watch one of the team’s lesser names in action.

Murray certainly did not have it all his own way against Karanusic, whom the now-retired Tim Henman had swatted aside on Friday, building the platform for Great Britain to wrap up this potentially tricky World Group play-off inside two days.

It looked like the Scot was set to enjoy little more than a glorified training session when he breezed into a double-break lead from the start, winning the first four games before Karanusic opened his account.

But the steely Croatian then broke Murray when the home favourite served for the set, giving some indication of the problems he would pose his opponent in the second set.

Murray had to rally back from an early break and saved another break point at 3-4 down before he gained the apparently crucial break at 6-5 which enabled him to serve for the match.

But the Scot spurned no fewer than four match points on his own serve and was dragged into a tie-break, where he held his nerve to wrap it up 7-4 and belatedly secure victory.