Andy Murray dug deep to see off Feliciano Lopez and make the quarter-finals of the Barcelona Open.

Having accepted a late wildcard to the tournament as he ramps up his fitness on clay courts, Murray was challenged throughout by the left-hander but eventually emerged a 6-4 6-4 winner.

An early exit in Monte Carlo and Bernard Tomic's withdrawal in the second round here had left Murray short of practice and the rustiness in his game was evidenced in a 10-minute opening-game hold.

Lopez gave the world number one's backhand a stern examination throughout and rallies between the pair were often long, drawn-out affairs as each player waited for the other's error.

There was some sparkling tennis on show, with both getting points from some thrilling battles at the net, but Murray's lasting power was showing through and a brilliant lob put him a break ahead at 5-3.

An identical shot handed Murray a third set point in the following game, and two more came and went before Lopez managed to dig out two Murray forehands at his feet and the Scot netted to give up the break.

He would not have to wait much longer for the set, though, as Lopez went long twice, though the epic games would continue into the second as the game reached 2-2 despite nine break points being carved out in the space of two games.

Suddenly both men had their serve working perfectly as games were rattled off at speed, until the 10th as Lopez errors had Murray 40-0 up and another wide shot sent Murray into the next round, where his conqueror in Monaco - Albert Ramos-Vinolas - could await if he beats fellow Spaniard Roberto Bautista-Agut.