consecutive major, had lost to Zverev in the first round on clay in Madrid earlier this year.
But he is an experienced Grand Slam competitor, making the last 16 in Paris on four occasions.
“I practised really hard before this match against a great player like Alexander and I am super happy to be here on this court,” said Verdasco who next plays France’s Pierre-Hugues Herbert.
“Maybe it was my experience. You have to be ready emotionally and physically because it can be a long match.”
Third seed and 2015 champion Stan Wawrinka was an easy winner, defeating Slovakian qualifier Jozef Kovalik 6-2, 7-6 (8-6), 6-3.
Juan Martin del Potro marked his return to the French Open after an absence of five years by defeating Argentine compatriot Guido Pella 6-2, 6-1, 6-4.
“I love to be playing this tournament again after five years,” said 2009 US Open champion Del Potro, who reached the quarter-finals in his last appearance in Paris before blowing a two-set lead against Roger Federer.
Taiwan’s Hsieh Su Wei, the World No 109, stunned seventh
Hsieh Su Wei returns a shot against Johanna Konta at Roland Garros in Paris yesterday.