ANDY MURRAY cruised past Gilles Simon to reach the quarter-finals of the Madrid Open and reported himself more than content with a second serve becoming an ever stronger element of his armoury.

Murray is more confident than ever of breaking his duck in the French Open at Roland Garros and continued his clay court campaign with a straightforward 6-4, 6-2 victory over his French opponent yesterday.

He won 75 per cent of his second serve points over the course of the match and admits that has been the direct result of some painstaking effort in practice.

“My second serve has improved a lot this year,” said Murray. “The pace on the serve is probably 15km an hour faster than it was at this time last year.

“I am getting a lot more kick on the ball. In my match against Radek Stepanek, I hit my second serve well too. He just returned unbelievably well at times and I still won 55 per cent of my second serve points, which is good.

“If you don’t hit your second serve well against Simon, he will have a crack at it, so I was able to get the ball bouncing up high to make it tough for him.”

The opening set went with serve until the 10th game, when Murray's relentless pressure finally told.

A stunning cross-court pass from the tightest of angles at 30-15 rattled Simon and Murray duly broke to take the set.

Murray then broke his frustrated opponent in the second game of the second set.

He had won five games in a row before Simon stopped the rot by holding serve in the fourth, but that was merely putting off the inevitable.

A lengthy delay in proceedings while a spectator received medical attention failed to knock Murray off his stride and another break sealed a routine victory.

“It was good,” said Murray, who will meet Tomas Berdych in the last eight. “I didn’t return that well at the beginning and missed a lot of returns in the first few games. When I got a rhythm on the returns, I was able to dictate a lot of the points and I used my variety well and served well.

“He wasn’t really able to put me under much pressure on my serve after my first couple of service games.

“He is obviously very tricky. He lulls you into a false sense of security in the points because he sits back and absorbs the pace very well. Sometimes, the better you hit the ball, the better it comes back off his racket.

“It is tough to get the balance between being patient and aggressive.”

Berdych reached the quarter-finals for the sixth year in a row as he defeated ninth seed David Ferrer 7-6, 7-5 in just under two hours.

The Czech clinched the opener on his fifth set point before prevailing in a second set that featured five service breaks.

The 30-year-old is bidding to reach the final in Madrid for the second time, having finished runner-up to Roger Federer in 2012. He goes into his quarter-final clash with Murray trailing 7-6 on the ATP Tour head-to-heads, but has won all three of their clay-court contests.

Novak Djokovic, meanwhile, recorded his 30th match win of the season to join Murray in the quarter-finals.

The Serb was in devastating form against Roberto Bautista Agut, the Number 15 seed, in a 6-2, 6-1 victory over 68 minutes. It was Djokovic's fourth straight win over the 2014 semi-finalist.

The World No. 1 is attempting to capture his 29th ATP World Tour Masters 1000 tournament and the fifth trophy of 2016.

He has recorded 30 wins, suffering just two defeats, over the year.

Sixth seed Kei Nishikori held off a late fightback from Richard Gasquet, prevailing 6-4, 7-5 in one hour and 40 minutes.

Nishikori held two match points as he served at 5-4, 40/15 in the second set, but Gasquet reeled off three straight points to fight his way back into contention. However, Nishikori broke again in the following game and closed out victory at the second time of asking.

In the men’s doubles, Jamie Murray will see his five-week reign as world doubles number one end on Monday following defeat in the Spanish capital.

Murray and his partner, Bruno Soares of Brazil, were beaten 6-4, 7-6 (7-4) in the second round by Finn Henri Kontinen and Murray's former partner John Peers.

Murray took over from Brazilian Marcelo Melo at the top of the standings following the Miami Open, becoming the first British player ever officially to be ranked world number one, but the points difference was small and it was always likely to prove a tough position to defend.