The Italian veteran capitalised on a lacklustre display from his British rival to snare his first victory at ATP level since the ABN AMRO in Rotterdam in February.
Edmund, who reached the first ATP final of his career last weekend in Marrakech, was below par for much of the encounter. Previous exertions perhaps contributed to his error-prone display, but it still remains a disappointing loss.
The British No.1 has had a curious campaign so far. He excelled in Brisbane, Melbourne and Marrakech yet failed to make in an impression at Masters events in Indian Wells, Miami and Monte-Carlo.
Grigor Dimitrov avoided the same fate as Edmund by recovering from a set down to defeat Pierre-Hugues Herbert 3-6 6-2 6-4 and reach the last sixteen. He awaits the winner of the Philipp Kohlschreiber versus Albert Ramos-Vinolas contest.
The Bulgarian has been struggling for form in recent months, however he finished his latest duel with a spring in his step.
Lucas Pouille was a surprise second round casualty on day three. The Frenchman, who reached the last four 12 months ago, was upended by Mischa Zverev. The German scored an unexpected 2-6 6-1 7-6(3) win, his first Top 20 success since the US Open last summer.
Elsewhere on the grounds on a busy afternoon, Feliciano Lopez took out Benoit Paire 5-7 7-6(5) 6-4, Richard Gasquet dismissed Jeremy Chardy 6-4 7-6(5), Diego Schwartzman eliminated Guido Pella 0-6 6-2 6-3 and Fabio Fognini delighted his supporters by moving past IIya Ivashka 6-4 7-5.