(CNN) -- Eighth seed Stanislas Wawrinka became the biggest casualty of this week's clay-court Barcelona Open when he was beaten in three sets by Czech Radek Stepanek.
Wawrinka's impressive clay-court form deserted him as he crashed out of the Barcelona Open on Thursday.
World number 19 Stepanek won 6-4 1-6 7-5, his third straight career victory over Wawrinka, who will now defend his title at the Rome Masters next week with his preparations cut short.
Swiss Wawrinka, a Davis Cup teammate of Roger Federer, reached the semifinals in Monte Carlo last week -- taking Novak Djokovic to three sets -- but could not reproduce that form in Spain.
Meanwhile, top seed Rafael Nadal maintained his relentless march towards a fifth successive Barcelona title by crushing Christophe Rochus.
Nadal eased into the quarterfinals with a 6-2 6-0 victory over his Belgian opponent, his 23rd consecutive clay-court win.
The Spaniard was due to face David Nalbandian, who put out 10th seed Nicolas Almagro 6-3 6-4, for a place in the last four.
However, the Argentine was forced to withdraw with a right hip injury, meaning Nadal can have a valuable day off with a semifinal place already assured.
Meanwhile, Spaniards David Ferrer and Tommy Robredo are also into the last eight after both recovered from dropping their opening sets.
Fourth seed Ferrer defeated Italian Potito Starace 4-6 7-5 6-2 while 2004 champion Robredo, seeded six, overhauled Russian Igor Andreev 4-6 6-2 6-3.
Meanwhile, in other tennis news, four-time champion Andy Roddick has confirmed he will play in the Wimbledon warm-up tournament at Queen's Club.
The American sat out the grasscourt event last year but will face stiff competition from defending champion Nadal and home hope Andy Murray.