Sixth-seed Albert Ramos Vinolas lost 7-5 6-2 to world number 255 Alexandre Sidorenko in a first-round match that lasted one hour and 23 minutes on Tuesday.
The victory was Sidorenko’s first on the ATP Tour in 2016, and he was pleased it came in his home town.
Next up for Sidorenko is Paolo Lorenzi, who staved off two match points to overcame Mischa Zverev 3-6 7-6 (8-6) 6-0.
Former world number seven Fernando Verdasco also fell at the first hurdle, despite taking a one-set lead against Dusan Lajovic.
Serbian Lajovic dominated the Spaniard’s second serve as he rallied from behind to win 2-6 6-3 6-2 and book a place in the second round.
In an all-Russian clash, qualifier Daniil Medvedev eased past wildcard Alexander Bublik 6-4 6-0.