Rome, Italy, 14 May 2011 | AP

Rafael Nadal will keep the No.1 ranking for at least another three weeks following an efficient 6-1 6-3 win over Croatia’s Marin Cilic in the Italian Open quarter-finals on Friday.

Nadal was at risk of losing top spot to Novak Djokovic if he failed to reach the last four in Rome, where the Spaniard has won five of the last six years.

His semifinal opponent will be 16th-seeded Richard Gasquet, who rallied to beat seventh-seeded Tomas Berdych 4-6 6-2 6-4 a day after eliminating Roger Federer.

“Yesterday all afternoon I had a fever but at the end of the day I started to feel better,” Nadal said.

“I started the match with (more) intensity and I was able to move faster and play more with my legs.”

In the other half of the draw, Andy Murray overcame a slow start to beat German opponent Florian Mayer 1-6 6-1 6-1 and become the first British man to reach the Rome semi-finals since 1932.

In women’s action, Australian Samantha Stosur got a measure of revenge on Francesca Schiavone by beating the Italian 6-2, 6-4 in a rematch of last year’s Roland Garros final. Stosur never dropped her serve and faced only one break point.

The crowd of 10,500 cheered loudly each time Schiavone held serve but Stosur’s play kept the fans from becoming too much of a factor.

“Of course I would rather win (the French Open) but I am happy to be here and be in the semis,” Stosur said.

“I think I played really well today and I do not think she played her best but that is because I played well and she could not find anything to do against me.

“Perhaps she was a little bit more nervous with the crowd behind and it made it a little bit more difficult with the expectations of flying high.”

She will play Li Na of China for a spot in the final after the Australian Open runner-up beat Greta Arn of Hungary 6-3 6-1.

Top-ranked Caroline Wozniacki overcame two-time Rome champion Jelena Jankovic 6-3 1-6 6-3 and will next face seventh-seeded Maria Sharapova, who advanced when Victoria Azarenka retired with an apparent right arm injury.

The third-seeded Azarenka won the first set 6-4, then called a trainer out to the court for treatment after losing the first game of the second set. She winced and bent over in pain during the next two games, then retired.

The fourth-ranked Murray also showed good clay-court form in Monte Carlo last month, taking a set off Nadal in the semi-finals.

“If I want to get to No.1 in the world then you need to play well on all of the surfaces because Roger, Rafa and Novak – they all play well on all the courts,” Murray said.

“I need to improve my game on the surface and it’s been better this year.”

The last British man to reach the semifinals at this event was George Patrick Hughes in 1932, while the last British player to win the title was Virginia Wade in 1971.

Murray’s semifinal opponent will be either Djokovic or Robin Soderling, who were playing in a night match.