WORLD number two Andy Murray remains on course to defend his Madrid Open title after beating Rafael Nadal in straight sets in their semi-final.

Murray, whose only previous victory on clay against the nine-time French Open champion came in last year's final, silenced the home fans inside the Caja Magica with a 7-5 6-4 win in two hours and 11 minutes.

The 28-year-old Scot raced into a 4-1 lead in the opening set and although Nadal broke back and got on level terms at 5-5, Murray broke serve to love in the 12th game, sealing the set with a thumping forehand return winner.

Nadal came out fighting in the second set and Murray had to save seven break points in his first four service games, but the former Wimbledon champion crucially needed just one chance to break for a 4-2 lead.

Murray served for the match at 5-3 but was unable to convert his first match point as Nadal broke back to keep the contest alive, only for the world number five to tamely surrender his own serve in the next game.

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Murray told Sky Sports: "I think I used my forehand pretty good during the match and I was able to push him back behind the baseline. I felt like I made a lot of returns in play so was able to make him work hard in his service games.

"Rafa doesn't serve as hard as everyone else but he puts a lot of pressure on your return because if you don't hit a good one he dictates the point straight away with the forehand. I was able to get some quite good direction on the returns and I think that helped me a lot today."

Nadal had recovered from a set down to beat Murray in the semi-finals in Monte Carlo last month, which made saving three break points at the start of the second set even more vital.

Murray added: "The beginning of the second set in Monte Carlo he came out having lost the first and really raised his intensity and I didn't. Today that first game in the beginning of the second, again he raised the intensity and had a few break point chances but I felt like I raised my level as well.

"It's easy after winning a tight first set to drop your intensity or your level and I really tried to stay on top at the beginning of the second and that was important."

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After beating Tomas Berdych in the quarter-finals, Murray spoke about the improvements he had made to his serve recently and revealed that involved his own research as well as working with his brother Jamie's coach Louis Cayer.

"I spoke to a number of coaches who work with younger players to develop technique, just to understand different grips, different positions to stand on the court as well, the ideal spot to make contact with the serve," Murray said.

"I spent a bit of time with Louis Cayer before Monte Carlo and watched a lot of videos. Sometimes you can get into bad habits over the years because when you become a professional you don't do as much technical work, it's more tactical and physical work."