Juan Carlos Ferrero dispatched Paradorn Srichaphan in straight sets to ease into the semi-finals of the Madrid Masters.
The top seed took just 65 minutes to defeat the Thai 6-4 6-2.
The win ensured that Ferrero remains at the top of the world rankings for another week at least.
His closest rival, Andy Roddick, crashed out in the third round.
The Spaniard will now meet Wimbledon champion Roger Federer for a place in the final.
Srichaphan had double-faulted in the seventh game to gift Ferrero a break in the first set.
The French Open champion continued to benefit from the seventh's seed unforced errors, breaking him twice in the second to wrap-up the match.
"When I went onto court, I forgot all about keeping my number one place," said Ferrero.
"If I thought about the ranking, I wouldn't be relaxed. I just try to beat the player that I'm facing, I just want to win the match. Anything else would be a mistake."
Federer was made to work for his semi-final meeting with Ferrero by the unseeded Spaniard Feliciano Lopez.
The 22-year-old claimed the first set 6-4 before Federer fought back to wrap up the next two 7-6 6-4.
"The game against Lopez was a big match but tomorrow against Ferrero is even bigger," said Federer.
"I'm playing a guy who is in contention as well. I just hope I can play well tomorrow and beat him.
"Ferrero didn't miss too much in his game today but he knows I will play aggressively."
Morocco's Younes El Aynaoui fought back from a set down to defeat Sebastien Grosjean.
The number 15 saw off the Frenchman, who had not lost a set on his way to the quarter-finals, 3-6 7-6 6-2.
Both El Aynaoui and Grosjean are vying for the last two spots in next month's season-ending Masters Cup in Houston.
With only the top eight players qualifying, Grosjean is currently 10th with El Aynaoui moving up to 12th.
"It was close but my serve helped me a lot," said El Aynaoui.
"I think my mental strength played a big part in it. It's a combination of good form and mental desire."
El Aynaoui will now meet Chile's Nicolas Massu , after he saw off the challenge of Argentine Juan Ignacio Chela 6-7 6-4 6-4 in a gruelling encounter which lasted two hours 57 minutes.