Del Potro had enjoyed a fairly comfortable route through to the third round of the competition, having not dropped a set against Dodig of Croatia or Seppi of Italy. He now faced a Frenchmen, who was also in superb form, having not dropped a set either as he had defeated Kukushkin of Kazakhstan and Dimitrov of Bulgaria.
It was the Argentine though who raced to a first set lead, winning it 6-1 in just 29 minutes. Simon rallied and won the seventh game of the second set to break Del Potro’s serve and he held is nerve to hold his own service game to win 6-4 and take the game to a deciding set.
Del Potro though was just edging the play and he was able to break the Frenchmen’s serve in just the second game of the third set, before seeing out the game for a place in the Quarter-Finals with a 6-1, 4-6, 6-3 win.
Elsewhere, eleventh seed Nicolas Almagro of Spain saw off the challenge of the un-seeded Steve Darcis of Belguim.
Darcis had sprung the first shock of the Olympic tennis tournament by beating sixth seed Berdych of the Czech Republic in the first round, before progressing past Giraldo of Colombia. Almagro had not dropped a set on route to the third round and kept up this record with a comfortable 7-5, 6-3 win over the Belgian to set up a tie with home favourite Murray of Great Britain.