The Team Sunweb rider clocked 50min 37sec over the 39.8-km course between Foligno and Montefalco, beating Britain's Geraint Thomas by 49 seconds and Luxembourg's Bob Jungels by 56.
There was no change at the top of the overall standings with Sunweb's Tom Dumoulin preserving his two minutes and 23 second lead over Movistar's Nairo Quintana, with Bauke Mollema (Trek-Segafredo) in third.
Thomas, who lost over five minutes after a crash in the ninth stage, revived his podium finish hopes, sitting in 11th place overall, 5:33 off the pace.
Maestri understandably opted to attack heading into the closing kilometres to put on a show in front of his local crowd, but was inevitably caught by the peloton as the sprint teams got into position. All I can do is thank my team.
Bennett did his best to better the two third places he has already achieved in this year's race but ultimately it was Gaviria who blazed home as the Colombian continues to impress.
French President Macron unveils 'gender even' Cabinet
Macron wants European militaries to work together more, and for eurozone countries to share a budget and tax rules. But Macron's office said the government line-up would not be unveiled until 3:00pm (1300 GMT) on Wednesday.
He added: "Laurens is our old warrior, he s getting better with age".
He managed to join Sky rider Mikel Landa in a two-man breakaway and when they were eventually reeled in by a counter-attacking group containing Portugal s former world champion Rui Costa, the Spaniard did well to keep some powder dry.
"And that's how I'm here with my third victory".
The Estonian launched a bid for stage victory in the final kilometre and, for a brief moment, it looked like the four leaders would be thwarted when the peloton came over the horizon with 400 metres to race.
"It's been a good day for me".
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