Delpo completes great day for Argentina

This will be the first time that Argentina has had two representatives in the men’s singles last eight at Roland-Garros for 13 years, since the 2005 edition, which saw Guillermo Canas and Mariano Puerta reach the same stage.

While Schwartzman now has the unenviable task of tackling 10-time champion Rafael Nadal in the quarter-finals, Del Potro’s triumph earns him a rather more winnable date with No.3 seed Marin Cilic, who looked relieved to repel a ferocious fightback from Fabio Fognini before prevailing 6-4 6-1 3-6 6-7(4) 6-3 in a compelling match that entertained the Court Philippe-Chatrier crowd for more than three hours 37 minutes.

The Croat, though, looks a particularly favourable match-up for Del Potro, who leads his fellow former US Open champ 10-2 on career meetings, including the last seven in a row stretching back six years.

“Well, we did a good day today,” Del Potro said of the Argentine success. “We both played good tennis. Diego played an unbelievable match, coming back from two sets down and breaking Anderson's serve many, many times and I'm looking forward to keep watching him in that level against Rafa.

“I know he has everything to do a good match, as well.”

The No.5 seed Del Potro, so popular among the Roland-Garros fans after his inspiring, uncomplaining fight to rebuild his career following constant wrist injuries, had a more straightforward-looking win, powering to a 6-4 6-4 6-4 victory over Isner in just under two hours, eking out one break of the American’s destructive serve in each set while his own delivery proved impregnable.

“It wasn't an easy match. John is very dangerous. I broke three times. I took all my chances. That was enough,” said Del Potro. “Being in the quarter-finals in a Grand Slam, in this particular Grand Slam, is very special, something I'm very happy about.”

So happy, in fact, that he ended up singing “Allez Les Bleus”, the theme song for France football followers, on court afterwards. “There was a lady singing all the time, like ‘USA’ and we are in France, and I know your song.

So that's what I did. I have great relations with the French fans, so I'm excited to keep playing here because they are so kind with me.”

Del Potro’s victory came just a few hours after Schwartzman - the more diminutive half of the burgeoning ‘little and large’ double act of Argentine tennis - came from two sets down for the first time in his career to beat Kevin Anderson.

“Personally, I'm happy for Diego, because in this case he is playing well,” said Del Potro. “He's getting close to the top 10. It will happen very soon. He deserves it - and he's playing well.”