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

But Murray certainly did not have it all his own way against Karanusic, who was beaten by Tim Henman on Friday.

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 broke his duck.

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 Murray 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.

The Croatians gained some consolation when Marin Cilic defeated Jamie Baker 6-4 6-4 in the remaining dead rubber to give Great Britain a final winning margin of 4-1.