Injured Murray is certain he will be fit for Wimbledon

Last year it was wrist-watch, this year it will be thumb-watch. Twelve months after Andy Murray kept his supporters in suspense as a wrist injury eventually ruled him out of Wimbledon, the 21-year-old Scot will go into his final week of preparations for this year's championships nursing a sprained thumb.

Having hurt his right hand against Ernests Gulbis in the Artois Championships here on Thursday, Murray pulled out of his quarter-final against Andy Roddick yesterday after testing the injury in practice. He said he hoped to be back on the practice court within three or four days and did not see any threat to his participation at Wimbledon.

"I wouldn't have damaged it any more by playing," Murray said. "It would just have prolonged the time that the thumb would have been painful. If I'd played today I still think I would have been OK for Wimbledon, but there's no point going on court feeling 50 per cent."

Having had trouble even picking up his phone yesterday morning, Murray took some anti-inflammatory medication before heading for the practice court. "I could hit the ball decently but I couldn't hit a backhand volley and slicing was very sore," he said. "I had a scan. I haven't pulled anything. I just sprained it a bit. It's not terrible, but it's just too sore to try and play a match."

Murray said he would take his recovery day-by-day. "I obviously want to get in some good practice over at Wimbledon," he said. "I need to get the swelling down as fast as possible. If I keep playing I won't be able to get rid of it, so I'll just take a few days off. I've played so many matches that it's not so much the match practice that's important, it's getting used to the movement and the feel of the ball on the surface."

While the injury is nothing like as serious as the damaged wrist tendons that kept him out for three months last summer, it is an unwanted interruption to Murray's grass-court preparations. There is only a fortnight between the end of the season on clay and the start of Wimbledon, by which time the world No 11 will have completed only one competitive match on grass – Sébastien Grosjean pulled out of Murray's opening match here with a thigh injury after only two games.

Although he played at Wimbledon in the Davis Cup in September, the win over Gulbis is the only tournament match Murray has completed on grass since his fourth-round defeat to Marcos Baghdatis at the All England Club two years' ago.

Murray plans to play at the Boodles Challenge exhibition event in Buckinghamshire next week, but it will be no substitute for a competitive match against an accomplished grass-court player like Roddick. The American, whose third-round opponent, Mardy Fish, pulled out with an injury after only one set, has won the Artois title four times in the last five years and in recent months has been in the sort of form that will again make him a serious contender at Wimbledon.

In today's semi-finals Roddick will play Rafael Nadal, who was given the perfect pre-Wimbledon work-out by Ivo Karlovic. The 6ft 10in Croatian, who has one of the biggest serves in the game, hit 35 aces, but Nadal won a match without a break of serve 6-7, 7-6, 7-6. The world No 2, who did not go beyond the quarter-finals in his two previous appearances here but still went on to make the Wimbledon final, served well and played the last two tie-breaks beautifully.

Nadal, who said he felt some pain in his right knee during the match, was asked about the experience of receiving a Karlovic serve on grass. "It's like facing a penalty," he said. "You have to guess where the ball will go. It's impossible to wait in the middle. You have a 50 per cent chance of guessing right, but even if you do that you still have only a 50 per cent chance of hitting a good return."

The Spaniard's pleasure at winning was tempered by the knowledge that his progress will delay his return home. "It's tough because I'll be missing Friday night in Majorca," he joked.

Whether he wins or loses today, Nadal is determined to spend three days back at his home island before Wimbledon. "I need three days off – four would be amazing," he said. "It would be impossible to be here any longer. I've spent nine days at home in the last four months. I need to play golf with my friends and family. I need to forget tennis for a few days."

Novak Djokovic, who lost in the third round here last year in his only previous appearance, reached the semi-finals with a 6-2, 6-2 victory over another four-times winner of this tournament, Lleyton Hewitt. Djokovic next plays the Argentine David Nalbandian, who beat France’s Richard Gasquet 6-4, 3-6, 7-6.