A potentially memorable final showdown between clay court king Rafael Nadal and in-form world number two Novak Djokovic at the Madrid Open moved a step closer last night as both players progressed through to the quarter-finals without any problems.
Top seed Nadal, who has won 35 successive matches on clay and is unbeaten on the surface since 2009, received a bye through to the last eight after his potentially dangerous third-round opponent Juan Martin Del Potro retired with a hip injury earlier in the day.
That tie had been the stand-out clash of the round, with Del Potro, the former world number four and 2009 US Open champion, looking on his way back to his best after missing most of 2010 having undergone wrist surgery.
The Argentinian had dropped to 484th in the rankings after playing just three tournaments last year, but he had climbed back up to 32nd spot aided by two title wins in 2011, the latest in Estoril at the weekend, and three further semi-final appearances.
Del Potro, who will also miss next week's Rome Masters as he returns to Argentina for treatment, said: "The pain started last week in Estoril, between the semis and the final, and the pain is getting worse day by day and I really felt it a lot today, so that's more reason for not playing."
Nadal will now play Frenchman Michael Llodra, who defeated Spanish qualifier Daniel Gimeno-Traver 1-6 6-4 7-6 (7/4).
Djokovic also went through as he made it 29 wins out of 29 in 2011 - the best start to a season since 1986, when Ivan Lendl also won 29 games on the trot.
Djokovic, looking for his sixth successive title this year, swept aside Spaniard Guillermo Garcia-Lopez 6-1 6-2 in just 51 minutes.
The Serbian said: "Confidence is obviously very high and at this stage it plays an important role in my game and I'm trying to use it to continue this winning streak.
"I'm taking one match at a time, focusing on my next rival and that's very important."
The two-time Australian Open champion will now sixth seed David Ferrer after the Spaniard eased past Sergiy Stakhovsky 6-3 7-6 (7/3) in his third-round match.
Third seed Roger Federer booked his place in the quarter-finals with a straight-sets win over Xavier Malisse.
Federer had survived a titanic battle in the second round against local boy Feliciano Lopez, saving a match point before winning 7-6 (15/13) 6-7 (1/7) 7-6 (7/5), but he had it much easier today as the Swiss superstar beat Belgian Malisse 6-4 6-3.
Federer's next opponent is fifth seed Robin Soderling, who recorded a 7-6 (10/8) 7-5 triumph over Jo-Wilfried Tsonga.
Number four Andy Murray was the first of the top seeds to bid farewell to the competition after he was beaten by Brazilian Thomaz Bellucci 6-4 6-2.
Bellucci now faces seventh seed Tomas Berdych, who defeated Juan Monaco 7-5 6-3.
Whereas the men's event will see six of the top eight seeds in the quarter-finals, it is a completely different story in the women's event following another day of upsets.
World number one Caroline Wozniacki, looking to win her fourth title of the year having reached five finals in her eight tournaments in 2011 previously, was defeated 6-4 1-6 6-3 by world number 27 Julia Goerges of Germany, who also beat the Dane in the final in Stuttgart last month.
Number three Francesca Schiavone and fifth seed Samantha Stosur were also knocked out today.
Schiavone was defeated 7-6 (7/5) 6-3 by Bethanie Mattek-Sands, while Stosur was beaten 7-6 (7/4) 6-3 by Anastasia Pavlyuchenkova.
Those three exits means eight of the top 10 seeds in the women's event have failed to get beyond the third round, with Vera Zvonareva (seeded two), Jelena Jankovic (seven), Maria Sharapova (eight), Shahar Peer (nine) and Agnieszka Radwanska (10) already out.
The only two to go through are Victoria Azarenka, the fourth seed, and number six Li Na.
Azarenka defeated wild-card Arantxa Parra Santonja 6-0 6-3 while Li Na fought back from first set loss to beat Roberta Vinci 2-6 6-2 6-1.