Andy Murray was sweating on an injury scare ahead of the quarter-finals of the Artois Championship.Murray injured his thumb, neck and groin in yesterday's third-round win over Latvia's Ernests Gulbis, and admitted the thumb injury was causing him greatest concern ahead of today's clash with defending champion Andy Roddick.The British number one was hoping to recover fully in time for the last eight showdown with four-time champion Roddick, with Wimbledon less than two weeks away.Murray said: "I am pretty concerned about it at the moment. With a sprain it tends to be worse the morning after but I will see what it is like in the morning before I decide what action to take."If I feel that I won't do it any more damage then I will play through the pain barrier but if it is affecting my grip and Roddick is serving at 140 miles per hour then obviously it's not the best thing for it."Murray, 21, missed the French Open and Wimbledon last year with a serious wrist injury and therefore is certain not to take any risks if the thumb injury turns out to be more serious than first thought.Although he was keen to get in as many matches on grass as possible before the third Grand Slam of the year, it is unlikely he will take any risks if medical staff at Queen's Club tell him there is any chance of making the injury worse by playing.Also in action today will be top seed and French Open champion Rafael Nadal, who faces 6ft 10in Croatian Ivo Karlovic in the last eight, with the winner set to face either Murray or Roddick in the semi-finals.The third quarter-final will feature second seed Novak Djokovic against former Wimbledon champion Leyton Hewitt after the Australian Open champion came through a tough third-round clash with fellow Serbian Janko Tipsarevic late last night.And the final quarter-final sees 2002 Wimbledon finalist David Nalbandian up against last year's beaten Wimbledon semi-finalist, Frenchman Richard Gasquet.