Esteban Chaves, who came into the day placed second overall, lost a flabbergasting 25 minutes, plummeting out of contention and in the process moving Bennett up a spot into sixth place.
Bennett, who finished the stage in 20th, 34 seconds behind winner Matej Mohoric, still sits a minute and 36 seconds behind leader Simon Yates at the race's halfway point, but he will have one less rival to deal with in the coming stages.
Additionally, any future attacks by Chaves - Yates' Mitchelton-Scott teammate - will no longer have to be respected as a threat by the title contenders, leaving the Australian team without a powerful potential tactic to employ.
Chaves' disaster was a capitulation which summed up the perilous nature of Grand Tours - one bad day - heck, just one bad moment - and your chances of overall glory disappear.
Today wasn't even meant to be a day where the favourites faltered - while it was the longest stage of the tour at 244km, it wasn't an extraordinarily tough route, and all of the other contenders safely arrived in the bunch.
That bunch included one of the favourites for the sprint - Sam Bennett - but he could only cross the line in third as breakaway companions Mohoric and Nico Denz battled for the stage win. Mohoric, a freakish descender, had escaped with 38km to go, and while Denz joined him 19km later, he ultimately didn't have enough firepower to sprint past Mohoric in the final metres, with the Slovenian claiming his second Grand Tour stage win.
While the finish was relatively straightforward, the start was challenging, and that was where Chaves found himself in trouble. A mere five kilometres into the stage, the peloton had to tackle a 15.7km climb, and Chaves was immediately dropped, suffering heavily after the rest day.
Chaves' Kiwi teammate - Sam Bewley - was sent to try and help bring him back to the group, and there was New Zealand involvement out front as well, with Tom Scully part of an initial 17-man breakaway.
However, with the peloton speeding up to try and suffocate Chaves, that breakaway was not allowed any room to breathe, with Scully - and eventually all 17 attempted escape artists - being reabsorbed by the main group.
It was a frankly chaotic opening to the stage, and a fascinating battle emerged. Two minutes down on the peloton, Chaves received assistance from Bewley and two other teammates to desperately try and bring him back, while Quick-Step helped them out to try and revive the chances of sprinting favourite Elia Viviani.
They got the deficit back to a minute, but for the rest of the peloton, this was a perfect opportunity to vanquish a contender. Bennett's team - Lotto NL-Jumbo - was one of the squads to hit the front, sharing the work with all the teams who also possessed general classification favourites.
It worked a charm. First Quick-Step gave up the chase, and soon enough, Mitchelton-Scott let go as well, giving up on Chaves' GC hopes, and in the process, putting all their eggs in the Yates basket.
It could be a fruitful basket, with Yates extending his lead to 41 seconds after taking bonus seconds at an intermediate sprint point, and he - and Bennett - nearly made further gains in a tense descent near the end of the stage.
Two of the five riders ahead of Bennett on GC - Richard Carapaz and Tom Dumoulin - both came to grief and required bike changes in the last 20km, but managed to get back to the peloton, leaving only Chaves as the major victim from the stage.
There could be another change amongst the general classification contenders tomorrow - albeit a likely small one - with stage 11 ending in an brief uphill finish which includes a gradient of 16% with 1.5km to go.
Positioning will be important once more, and time could be lost if the favourites aren't at their best - something Chaves found out in brutal fashion this morning.
