Back in the bunch, things were going steady - Rafal Majka set a strong early tempo as the gradient hit double digits in a tough middle section, and Bennett hung around at the back of the ever-decreasing group.
He would move up behind teammate Sepp Kuss as Majka's effort ended, but just as it looked like all the big favourites had negotiated the toughest portion of the climb, the attacks finally came.
Miguel Angel Lopez started the moves, matched by Nairo Quintana and initially Bennett, but a surge from Wilco Kelderman proved decisive. Lopez, Quintana and Kelderman rode away, gaining three seconds on Rigoberto Uran, six seconds on Ion Izagirre, nine seconds on Yates, and 22 seconds on a fading Bennett.
Despite his late suffering, Bennett hung on to take back slivers of time on some of his other rivals for the general classification, moving back into 10th, 48 seconds behind Yates who just did enough to take a one second lead over Alejandro Valverde.
The riders get a well-deserved first rest day overnight, before the Vuelta resumes with a flat stage 10.
Elsewhere, Patrick Bevin's quest for a top finish has begun at the Tour of Britain.
With no major mountains and a team time trial on the agenda for the race, the course suits Bevin, and as a result he has been included in the top 10 favourites at the bookmakers for the title, notably alongside the likes of Chris Froome, Primoz Roglic and Geraint Thomas.
Bevin is one of six New Zealanders in action, including James Oram and Hayden McCormick, who will both be looking for a new team next year after their One Pro Cycling outfit announced they would not be fielding a men's team in 2019.
The news follows that of Aqua Blue Sport's folding last week, which has left the off-contract duo of Aaron Gate and Shane Archbold looking for new pastures as well.
Of the six Kiwis, five finished in the leading bunch on the opening stage won by Andre Greipel, with only promising 20-year-old James Fouche losing time.