Rafael Nadal showed incredible grit to extend his run of consecutive sets won on clay to 42 in an enthralling Barcelona Open quarter-final against Martin Klizan.

World number one Nadal saved three set points to avoid dropping a set on the dirt for the first time since last year's Internazionali d'Italia, before closing out a hard-fought 6-0 7-5 triumph.

The Spaniard must claim an 11th title in Barcelona to stay above Roger Federer at the summit of the rankings and he was given his first scare of the tournament by the searing forehand of Klizan, who accounted for Novak Djokovic in the second round.

Nadal let out a roar when he finally drew level in the second set and Klizan's resistance crumbled as the Spaniard notched a 17th straight victory on clay, while a semi-final win will be his 400th on the surface.

The 31-year-old wasted no time in setting about securing an advantage, forcing Klizan into a corner from which his cross-court return landed in the tramlines to give up the break on his opening service game.

Klizan attempted to keep his relentless opponent at bay, rushing to the net to pass Nadal's exquisite drop-shot back down the line, but a ferocious forehand extended the Spaniard's advantage.

The opening set was rounded off in just over half an hour, yet the Slovakian started the second on the front foot and consolidated an early break to put the 'King of Clay' under pressure.

Klizan dug in, producing a magnificent sliced drop-shot from the baseline before varying his game to hold to love with a serve and volley for a 4-2 advantage.

Despite causing Nadal problems with some stunning groundstrokes, a trio of misses on set point proved costly for Klizan, who handed his opponent a break when his forehand landed wide.

The Slovakian went long with an attempt to force a tie-break and with Nadal refusing to go away, a mishit from the baseline kept the Spaniard's incredible streak going.