Djokovic, playing only his second clay match of the year following elbow surgery, dropped the middle set and was tied at 4-4 in the decider before edging the final two games to secure a nervy 6-2 4-6 6-4 win over the Spaniard.

The Serbian is the top seed left in the tournament following world number one Andy Murray's shock defeat to Albert Ramos-Vinolas earlier on Thursday.

And Djokovic will now face Belgian David Goffin, who beat Dominic Thiem in three sets, for a spot in the semi-finals.

Djokovic joined Rafael Nadal in the last eight in Monte Carlo after the 30-year-old nine-time French Open winner demolished highly-rated German Alexander Zverev 6-1 6-1.

Nadal, who was taken to five sets by Zverev at the Australian Open earlier this year, will now face Diego Schwartzman of Argentina in the next round.

There were wins too in Monte Carlo for fifth seed Marin Cilic, who knocked out Tomas Berdych in straight sets, while number 11 seed Lucas Pouille secured his passage through to the quarter-finals after his French compatriot Adrian Mannarino retired in the first set.

But there was a surprise exit for Stan Warwinka after the number three seed joined Murray in departing the tournament at the last-16 stage.

Warwinka, the three-time major winner, was beaten in straight sets by Uruguay's Pablo Cuevas 6-4 6-4.