(REUTERS) – Roger Federer and Novak Djokovic joined Andy Murray in the semi-finals of the Dubai Tennis Championships after straight-sets victories and Juan Martin del Potro who defeated the fourth seed Jo-Wilfried Tsonga. Murray wasted six match points before overcoming Tomas Berdych 6-3, 7-5 after struggling with what appeared to be a leg injury in searing desert sun.
Seven of the world’s top 10 players had made the Dubai quarter-finals and Murray went into his last-eight match hoping to improve on a 3-1 losing record against the 26-year-old Czech.
Britain’s Murray appeared to be cruising at one set up and 2-0 ahead in the second, but then double-faulted to gift Berdych a break back for 2-2.
Murray’s movement was increasingly laboured but his reply was immediate, breaking again, only for Berdych to do the same and level at 3-3.
The Czech was ascendant and looked as though he could square the match, but Murray dug in and broke once more, playing a forehand cross-court shot from wide of the tramlines that Berdych had no reply to for a 6-5 lead.
Murray 24, wasted six match points on serve. The first three were with backhands that found the net and a fourth with an errant forehand drive. He eventually triumphed after Berdych played a long forehand.
Murray said of his injury: “I had a problem with it (the knee) since Brisbane and it’s come and gone.
“It was a bit sore right before the tournament. I didn’t feel it at all in the first couple of matches, and then right at the beginning of the second set I felt it.  It’s not something that stops me sort of running around. I want to try and get rid of it, because there are a lot of the big events coming up.”
Murray started against Berdych strongly, holding serve to love in the opening game before playing a leaping backhand that his opponent could only scuff into the net to give the Scot three break points in the next game.
The 2010 Wimbledon finalist saved the first two with huge serves, but on the third he shanked a backhand long to give Murray the break and a 2-0 lead, but the Scot had a scare in the next game, saving three break points before going 3-0 ahead.
The rest of the set went with serve as both players hugged the baseline on a soporific centre court, the stands barely half full and temperatures topping 30 degrees Celsius.
Berdych had one more chance to break back at 5-4 down, but the world number seven played a forehand long following a grinding rally and Murray took the first set with an angled forehand into the corner. The stooping Czech could only slug into the net.
Murray’s solitary defeat of 2012 came in a five-set epic against Djokovic in the semi-finals of the Australian Open and he will meet the Serb in the last-four in Dubai after the world number one overcame compatriot Janko Tipsarevic 6-1, 7-6.
The current ATP Dubai title-holder looked set for a comfortably journey into the semis when he broke Tipsarevic’s serve twice en route to a decisive first set, but was unable to shake off the improved performance of his opponent in the second set until he came from behind in a gripping tie-break.
Indeed, Tipsarevic looked good to force a third and final set when he raced into a 4-1 lead in the second set decider, only for the top seed to claw back to four apiece before taking the lead in the tie-break for the first time at 7-6 after surviving a set point to complete the straight-sets triumph.
Federer made short work of Mikhail Youzhny in his quarter-final, beating the Russian 6-3, 6-4 in 69 minutes.
Youzhny went for broke with ultra-aggressive shot-making, but his erratic execution meant he succumbed without forcing a break point on the Federer serve.
The Swiss improved his career record against Youzhny to 12-0, and will face Del Potro in the last four following the Argentine’s 7-6, 6-2 win against Tsonga of France.
Last week’s Marseille Open victor could not be separated from Tsonga over twelve games in the opening set, but sprang to life in the resulting tie-break, as Del Potro took the first five points in a row, before going on to clinch a 7-1 tie-break win with a majestic ace, and from there he didn’t look back.
Two breaks of Tsonga’s service led to Del Potro claiming the first four games of the second set on the bounce, and though Tsonga was eventually able to hold his serve on two occasions, the Argentine did the same to wrap up a comprehensive 6-2 set and book his place in the final four.