Top seed David Ferrer was knocked out of the Abierto Mexicano Telcel in Acapulco by Alexandr Dolgopolov earlier today.
Thirty-three-year-old Ferrer had been tipped to overcome his Ukrainian opponent in relatively straightforward fashion.
However, it was Dogopolov that won through 6-4 6-4 to book his place in the quarter-finals, where he will face Robin Hasse.
World number 32 Dolgopolov has already reached the last eight at tournaments in Sydney and Rio de Janeiro this year.
