As the Vuelta enters its home stretch, riders left the mountains behind in a flat 177.5-km ride from La Baneza to Iscar, speeding through the countryside at 80 km/hr at one point.
A breakaway group of four were caught with 20 km to go before the teams set themselves up for the sprint with Ineos Grenadiers, Movistar and Bahrain Victorious driving the bunch.
Once the riders rode through a final right-hand bend, they had a straight 2.2-km run to the finish line where Kaden Groves, who has won two stages, was involved in a crash where several riders fell after a touch of wheels.
Filippo Ganna was in the ideal position at the front and opened up the final sprint but Dainese timed his sprint to perfection to edge out his fellow Italian by milliseconds.
"We did a super job... Today we executed the plan, 100%," Dainese said. "It was really unlucky to lose a couple of guys in the crash but until that point I was in the perfect position, I was where I wanted to be.
"I knew there was a bit of a headwind so I just let Ganna and the other guys go a bit early and then I was waiting for my moment to go in the wind. I'm super happy to finish a hard Vuelta in this way."
Dainese said the victory was special as he is leaving the team for Tudor Pro Cycling next term.
"I really wanted to end the season in a good way and also to end my adventure with DSM in a good way," he added.
"Today I felt a lot of pressure because I knew it was the last opportunity for a sprint. I want to thank my team, they did a good job."
Kuss, two stages away from winning his first Grand Tour, was all smiles as he retained the red jersey. He leads fellow Jumbo-Visma riders Dane Jonas Vingegaard (17 seconds) and Slovenian Primoz Roglic (68 seconds).
"These stages are more stressful now because normally I sit at the back and go to the finish line, but now there's a bit more to lose," Kuss said with a laugh.
"There was always an annoying wind from the side, it wasn't too easy but there's no easy day in the third week... Luckily I stayed out of trouble (when the other riders crashed)."
