Andy Murray has admitted he needs to improve his serving if he is to increase his chances of winning, as he enters the final phase of his recovery from hip surgery.
The three-time Grand Slam winner made it two wins in two days as he followed up Thursday's win over Pablo Cuevas with victory over Marius Copil in the quarter-final of the European Open in Antwerp.
Murray needed two hours and 36 minutes to beat the Romanian after failing to serve out the match at 5-3 in the second set, but he eventually prevailed 6-3, 6-7 (7-9), 6-4.
It is good going for a player who had career-saving hip surgery at the start of the year and has only played a handful of singles matches.
"It's just difficult [in] tennis, because you don't get the opportunity to just come in and play one set like you might in other sports and build up your fitness by playing a little bit longer each time," Murray told ATPTour.com after his latest win.
"You need to get it through playing matches and maybe at that stage I just wasn't quite ready physically for long matches. But now obviously my body's getting a little bit more used to it and coping fairly well."
Murray was broken once in the first set by Copil and failing to serve out the match in the second set nearly came back to haunt him.
The former world No 1 admits it's an area that he needs to work on.
"Things obviously are going in the right direction and I feel like I'm hitting the ball better from the back of the court," he said.
"I just need to improve the serving, and if I do that then I'll give myself a lot of chances in matches."