Bennett had already won the green jersey – for the most consistent sprinter – at this year’s Tour de France, where he also picked up two stage wins.
And he showed he has taken that form into the Vuelta on a relatively calm fourth stage after the mountainous opening three days to the third and final Grand Tour of 2020.
Belgium’s Jasper Philipsen had made an early break for the line but Bennett got in his slipstream to pull clear and take the win.
The result had no bearing on the overall standings, with Primoz Roglic still leading Martin by just five seconds.
Meanwhile, the Giro d’Italia turned into a farce at the start of the day as riders refused to tackle the full distance of the 19th stage which, at 258km, was set to be comfortably the longest of this year’s race.
So, in a compromise with race organisers RCS Sport they were bussed to 124km to go until the finish.
A day of attacks followed and Josef Cerny made his stick with 21km remaining for the stage win. Britain’s Tao Geoghegan Hart remains in third and 15 seconds behind race leader Wilco Kelderman around of tomorrow’s mountainous penultimate stage.