Juan Monaco became the only seed in the men's draw to fall on day one when the injury-stricken Argentine crashed 7-6 6-1 6-1 to Andrey Kuznetsov.
The 11th seed took several lengthy time outs for treatment on his lower back and hips and was clearly struggling after dropping the first set tie-break.
Kuznetsov, the world number 78 from Russia, sealed victory with his sixth ace of the match and will meet South African Kevin Anderson or Paolo Lorenzi of Italy in the second round.
Also in the late session eighth seed Janko Tipsarevic was given a workout by a typically ebullient Lleyton Hewitt, eventually going through 7-6 7-5 6-3.
Veteran Hewitt had his chances despite dropping the opening set 7-4 in the tie-break, breaking twice in the second only to suffer three reversals on his own delivery.
He then dropped serve again early in the third and although he broke back to give the vocal crowd renewed hope, the Serbian broke again and this time made it stick.
Fourth seed David Ferrer eased past Belgian Oliver Rochus 6-3 6-4 6-2 while there were also wins for 20th seed Sam Querrey over Daniel Munoz and 24th-ranked Jerzy Janowicz against Simone Bolelli.
Radek Stepanek, seeded 31, got the better of a titanic struggle against Viktor Troicki of Serbia 5-7 4-6 6-3 6-3 7-5 - the veteran Czech eventually securing his passage into the second round in just under four hours.