Portugal Colonial - Djokovic into French Open quarter-finals after five-set thriller

The world number one shrugged off an injury to his right knee as he came from two sets to one down to outlast Cerundolo 6-1, 5-7, 3-6, 7-5, 6-3 after four hours and 39 minutes.

Victory gave him a record 370th Grand Slam win, eclipsing the mark he had shared with Roger Federer.

"Three or four times I was points away from losing this match and thank you to my opponent," he said.

"He deserves so much applause that's for sure. I'm not sure how I won this match again.

Djokovic will play Casper Ruud, the player he beat in last year's final, or Taylor Fritz as he continues his bid for a record-breaking 25th Grand Slam title.

The 37-year-old Djokovic, coming off a five-set match in the third round that ended at 3.07am on Sunday morning, repeatedly received treatment for an injury to his knee after taking a medical timeout early in the second set.

But he once more displayed his immense powers of recovery, crucially retrieving a break in the fourth set to stay on course for a fourth French Open crown.

Djokovic rolled through the opening set against Cerundolo on the back of two service breaks, but his problems arose in the second as he summoned the trainer.

The Serbian had his knee worked on while lying flat on his back on a towel, and immediately found himself under pressure once play resumed.

After failing to convert any of seven break points over three different games, Cerundolo finally seized his chance with Djokovic serving to stay in the set.

Djokovic steered a forehand wide to hand Cerundolo the second set and the 25-year-old carried that momentum in the third as he surged into a 3-0 lead.

- Court complaints -

The Serbian had complained about the state of the clay in his previous match against Lorenzo Musetti.

Blaming the court for "screwing up" his knee, Djokovic again pleaded in vain for the clay to be swept at more regular intervals.

Djokovic appeared consigned to the fact he would need to go the distance again, just as he did against Musetti, as Cerundolo closed out the third set with ease.

Cerundolo, seeking his first Grand Slam quarter-final, stood two games away from the biggest win of his career after breaking Djokovic and then consolidating for a 4-2 edge in set four.

As he has done countless times, Djokovic dug deep into his reserves to claw his way back level at 4-all as Cerundolo speared a shot into the net.

Djokovic unleashed a bellowing roar after holding in the next game, whipping up a crowd that sensed the three-time French Open winner was not done just yet.

He saved a break point to nudge 6-5 ahead and Cerundolo eventually became the first to blink, the top seed capitalising on a fourth set point to force a decider.

It felt almost inevitable Djokovic pinched a break to open the fifth set. Cerundolo to his immeasurable credit did not go away though.

The Argentine scrambled his way back on serve and Djokovic again vented his ire at the court conditions after an awkward tumble.

An attempted passing shot from Cerundolo had Djokovic at full stretch doing the splits, an indicator of the tremendous quality still produced from both players despite being tested to their limits.

Djokovic pounced on his opporunity when it arrived in the eighth game, ripping a forehand winner that clipped the baseline to earn the vital break before he sealed another incredible victory.

R.Veloso--PC