The Russian broke the Spaniard five times on his way to victory and will take on Pablo Andujar in the quarterfinals.
Simon was pushed hard in the opening set but eased through the second for a 7-5, 6-1 victory.
In a day of shock defeats, Morocco native and world No. 617 Lamine Ouahab fought from a set down to beat world No. 34 Philipp Kohlschreiber 2-6, 6-0, 7-6. Nikoloz Basilashvili now awaits in the second round.
Kyle Edmund found out his last-16 opponent after Romanian Radu Albot overcame Italian Andreas Seppi 1-6, 6-3, 6-0. If the British No. 1 finds his way past Albot, a meeting with either Mischa Zverev or wild-card Malek Jaziri awaits after the latter fought from a set down to beat Marton Fucscovics 1-6, 6-4, 6-2.