Argentina’s unheralded Guido Pella created the shock of the opening round at the RIo Open on Monday after felling fourth seeded American John Isner.
In his Rio Open debut, World No.71-ranked Pella squeezed through the first set winning it on a tiebreak and then had a match point with Isner serving at 4-5 in the second.
But Isner kept his cool to level the game at one set apiece and send the tie into a decider.
Isner recovered from a second match point late in the third which eventually went to a match-deciding tiebreak.
In the breaker Isner had three match point opportunities of his own only to be denied by Pella who went on to seal a shock victory on his match point No. 3.
He now faces a second-round showdown with Colombia’s Santiago Giraldo.