Artois Championships: Monday 9 June to Sunday 15 June Coverage: BBC TV, BBCi, Radio 5 Live and the BBC Sport website.
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Murray was relieved not to pick up a serious injury
Andy Murray survived an injury scare before defeating Latvia's Ernests Gulbis 5-7 6-1 6-4 to reach the last eight of the Artois Championships.
Both players struggled with their footing on a damp day at Queen's Club, and play was briefly suspended at 2-2.
And moments after levelling at one set all, Murray screamed in pain when he fell while quickly changing direction.
After a medical time-out he returned to seal the win, but is a doubt for the rest of the tournament.
Top seed Rafael Nadal had a surprisingly testing encounter against 18-year-old Kei Nishikori of Japan, eventually coming through 6-4 3-6 6-3 to set up a quarter-final against eighth seed Ivo Karlovic, who beat Fernando Gonzalez 6-3 7-5.
World number three Novak Djokovic also had to come back from a set down in his first meeting with fellow Serbian Janko Tipsarevic.
Djokovic eventually dug out a 2-6 6-1 6-4 win and faces four-time champion Lleyton Hewitt, who beat Paul-Henri Mathieu 6-4 6-4, next.
Murray is due to face Andy Roddick next - the defending champion went through when Mardy Fish retired with an ankle injury after losing the first 7-6.
"My groin and neck are okay but the thumb is pretty sore," said Murray. "I'm pretty concerned about it right now.
That's the first time I've been on a tennis court and been more worried about getting through the match uninjured
"A sprain tends to get worse the next day but I can play through the pain barrier if it's not affecting my grip and as long as the doctor says I'm not going to make it worse.
"I'll see what it's like in the morning and if it's worse then I will try to get something done. I'm guessing it will be fine for Wimbledon but the next couple of days might be a bit tricky.
"If I can't hold onto the racquet properly, and Roddick is hitting 140mph serves, that's probably not the best thing for a sprain, I guess."
Gulbis, ranked 51 in the world and rising, was always going to be a tough opponent for Murray having reached the French Open quarter-finals.
After a brief rain interruption at 2-2, the opening set came alive in game 11 and it was Murray who came off worse.
The Scot was unfortunate to go break-point down when Gulbis slipped and fired a backhand so far long that it clipped Murray around the waist, giving the Latvian the point.
Andy Murray was concerned about the slippery conditions
It became apparent moments later that Gulbis did not realise he had won the point, as he lost a lengthy following rally and promptly headed for the changeover unaware that it was in fact deuce.
However, Murray could not make him pay as he produced his first double-fault of the match two points later to give up the break and immediately called for the trainer to treat his thumb, which he hurt when tumbling at the net.
Murray did well to earn a break-back point in the following game with a precise forehand steered down the line, but Gulbis saw off the danger impressively by attacking the net to wrap up the set.
The understandable frustration of dropping such a tight set looked to be getting to Murray at the start of the second but he just about kept his temper in check, and played a superb game to finally break Gulbis in game four, taking it with a deft drop shot.
And the Briton's confidence was boosted further in the following game when, from 15-40, he managed an ace, a forehand winner, a second ace and another deadly drop shot.
With both players looking increasingly uncertain on the slick surface, Murray capitalised with some heavier hitting and grabbed another break to quickly seal the second set.
There were worried looks all round when Murray went down heavily at the start of the third but a medical time-out apparently did the trick.
And in a high-quality final set, Murray made the decisive breakthrough in game nine when he chased down a smash and did enough with the backhand to force a poor volley from Gulbis.
A fired-up Murray confidently served out for a fine win in exactly two hours.
"That's the first time I've been on a tennis court and been more worried about getting through the match uninjured," Murray told BBC Sport afterwards.
"It was so slippy out there and even when it's only a little bit of rain I'm sliding two metres after every shot, and changing direction is so hard as well, so I was just really glad to come through in the end."
In other matches, David Nalbandian was too strong for last year's Artois runner-up, thrashing France's Nicolas Mahut 6-4 6-1.
And fifth seed Richard Gasquet of France had an excellent 7-6 (7-5) 6-4 win over Croatia's Mario Ancic.
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