BARCELONA (AFP) - Rafael Nadal's clay-court juggernaut roared ahead on Thursday, the Spaniard winning his 100th match from 101 on the surface to reach the quarter-finals of the Barcelona Open. Nadal worked for one hour, 45 minutes to beat friend and 16th seed Feliciano Lopez 6-4, 6-3. The three-time Roland Garros champion has not been beaten on his favoured surface since starting in the Monte Carlo first round three years ago. His only defeat during his run of form came in the Hamburg final last spring to rival Roger Federer, who swept a 6-0 fifth set. "I'm happier to be in the quarter-finals in Barcelona, I'm not thinking about the victories," said the world number two, who faces a fast turnaround when he meets Juan Chela Friday. "This is one of my favourite events and playing Feliciano is always tough," added Nadal, who had his left shoulder taped after complaining of pain in recent days. Nadal never faced a break point in a contest in which the first three games took 21 minutes to complete, including a third game with eight deuces and three break points saved by Lopez. A player from the host nation has won the event for six of the past seven years. Nadal's win meant four Spaniards from six moved into the last eight and Nicolas Almagro made it five when he beat Croatian Mario Ancic 7-6 (7/5), 6-2. Nadal is treading a fine line between winning while not running out of steam prior to his run at a fourth straight trophy in Paris from May 25. The Spaniard faces title defences here and in Rome before the French Open after winning his fourth straight in Monte Carlo last weekend over Federer. Spanish second seed David Ferrer laboured before finally overcoming persistent Nicolas Lapentti of Ecuador 4-6, 6-4, 6-3, taking two and a half hours to get the job done. Compatriot Tommy Robredo, the sixth-seeded champion from 2004, ended the run of Argentine Guillermo Canas 6-1, 7-5. Swiss Stanislas Wawrinka sprang a surprise on erratic Argentine third seed David Nalbandian 6-3, 6-1. "It was a tough match for me," said Nalbandian, the 2006 semi-finalist. "I was not the favourite at all, but that's normal for me." "I'm 27th and he's seventh," said the Swiss, who ran his record in the series to 5-2. Albert Montanes joined his mates in the Spanish Armada, getting past tough Russian qualifier Mikhail Kukushkin 6-3, 3-6, 6-3 and next plays Wawrinka. "I expect to have problems with him," said Wawrinka. "He's playing at home." Ferrer needed all of his bulldog determination to put down Nicolas Lapentti, ranked 83rd now but standing sixth in the world nine years ago. The Spanish favourite led early but was unable to impose, with Lapentti winning five of the last six games in the first set. Ferrer started to regain control with a break in the tenth game of the second to level and rode a break in the third to the hard-fought victory. Ferrer will face off on Friday against Robredo, whom he leads 2-1, including a win last month in Valencia.