BARCELONA (AFP) - Rafael Nadal rescued his dream of a fourth straight trophy at the Barcelona Open, turning the first-set tide to swamp Juan Chela 6-4, 6-2 on Friday in their quarter-final. Spain's world number two wore an uncharacteristic look of frustration trailing an early break against the baseline grafter from Argentina, ranked 37th with four career titles. Down 4-2, Nadal put in a Herculean effort in the marathon 20-minute eighth game, forcing Chela to fight off three break points over the course of eight deuces. Nadal finally got what he wanted on his fourth effort when the South American netted a backhand, 3-4. From then on, the three-time Barcelona holder took control in his usual fashion, wrapping up the opening set in 64 minutes and breaking to start the second on his way to victory in one hour, 42 minutes. "When Chela had points for 5-2, it was tough," said the treble Roland Garros champion. "But it was more manageable at 3-4 instead." The king of clay, on a mission to defend titles not only at the Real club but also in Rome and Paris in coming weeks, has now won 101 of his last 102 clay matches, last losing in the Hamburg final a year ago to Roger Federer. Nadal will play in a Saturday semi against either tenth-seeded Spaniard Nicolas Almagro or German surprise packet Denis Gremelmayr, who beat fourth seed James Blake. "I'm just glad to be in my fourth straight semi here. I'd like to win the tournament again, but I have a semi-final to play first. "It was a tough match all around and I had to work hard. I just want to do my best to win again." Swiss Stanislas Wawrinka beat Spain's Albert Montanes 6-3, 6-7 (6/8), 6-4 at an event where locals have won six of the last seven editions. The Davis Cup player made a stand on the clay to reach his second semifinal at the Real club. Second seed David Ferrer put a local into the last four, stopping number six compatriot Tommy Robredo 7-6 (7/4), 6-4 to line up against Wawrinka. The pair played for two hours, five minutes, producing nearly 50 unforced errors between them in the battle. Wawrinka needed almost three hours to struggle past Montanes, ranked 87. "I needed to play very aggressive," said Wawrinka. "I had to take chances as he's such a good clay player. "I should have closed it out in two sets, but I couldn't capitalise on all of my chances. "Still, I played a good match, it's great to go through again." Montanes did not help his chances in the duel, striking six double-faults and losing serve four times. Wawrinka was broken while serving for the match at 5-3 but returned the favour a game later to move through after holding a 5-2 lead and a match point in the second set. Wawrinka was playing in his third quarter of the season, reaching January's Doha final where he lost to Andy Murray. He played an Indian Wells quarter against Novak Djokovic and improved to 17-8 on the season.