Rafael Nadal remained the only one of the "Big Four" still standing Friday after third seed Andy Murray joined Novak Djokovic and Roger Federer in exiting the Madrid Masters.
Nadal dropped the opening set to fellow Spaniard David Ferrer and trailed 4-2 in the second before mounting a typical comeback to reach the semifinals.
But Murray, playing in the night session, was beaten 7-6 6-4 by Czech Tomas Berdych.
Murray, who will still take over as No.2 from Federer in the new rankings, was a break up in the first set but could not press home his advantage and a single break for the big-hitting Berdych in the second was enough to see him through.
In the women's WTA event in the Spanish capital, Serena Williams and Maria Sharapova remained on course for a final showdown as both reached the last four, but by contrasting routes.
No.1 Williams was given an almighty scare by wildcard Anabel Medina Garrigues before winning 6-3 0-6 7-5.
The American superstar had not dropped a set all tournament until being blanked in the second set, only the seventh time in her career she had suffered such a fate.
"I wasn't really there, my feet weren't moving -- I don't know what happened," she told the official WTA website.
Read: Djokovic dumped in Madrid by Dimitrov
"To turn it around I got up earlier on the changeover and started doing high knees and just stretching and doing anything to try to get my intensity back up to where it needed to be."
She will face Italian Sara Errani in the semifinals Saturday while Sharapova reached that stage with a 6-2 6-4 cruise against Estonia's Kaia Kanepi.
Sharapova will leapfrog Williams to No.1 if she can go one round further or beat her in the final should both reach it.
"I was just really determined today, and I'm happy I was able to win with that type of scoreline," the Russian said after her passage to the semifinals where she will play former No.1 Ana Ivanovic of Serbia.
Nadal later emerged on Center Court for a battle royale with Ferrer, who dominated the early sparring.
He took the opening set 6-4 in 51 minutes and was a break up in the second before the former No.1 hit back by taking the next three games.
Mallorcan Nadal served for the set at 5-4 but was broken by Ferrer as the match went to a crucial tiebreak.
It was comfortably won by Nadal who swept through the decider for a 4-6 7-6 6-0 win, his 18th in 22 clashes with Ferrer.
Nadal is looking to reach his seventh straight final since returning to the ATP Tour after injury in February and his beaten opponent knows only too well his abilities.
"Rafa is always the favorite on clay," he told the official ATP website. "Without any doubt he's the best and he's really fit right now."
Nadal will play Pablo Andujar for a place in the final after his fellow Spaniard ended the run of Federer's conqueror Kei Nishikori of Japan in straight sets 6-3 7-5 later Friday.
Berdych, bidding for a second straight Madrid final, will take on Swiss Stanislas Wawrinka, who put out seventh seed Jo-Wilfried Tsonga of France in a three-set late night thriller.