Despite another punishing category-two climb to the finish over the Alto de Naranco, a 12-man breakaway was never reeled in by the peloton after building up a five-minute lead.
Froome remains third overall but is now 27 seconds back on Quintana with Valverde second, just 19 seconds adrift of his Movistar teammate.
The gap he established over race leader Nairo Quintana was enough to leapfrog him in the overall standings, and he will take a 22-second advantage into stage 10. "I was so close to winning the stage, that was my main objective", said De la Cruz.
The remainder of the break - which had formed after 9km on the road and built up a maximum lead of over 10 minutes - trickled over the line in dribs and drabs before Quintana led the rest of the field home for 12th place, nearly five minutes down on Lagutin. "We are still feeling strong and riding well as a group".
Having worn the red jersey and helping Team Sky win the time trial, Kennaugh now sits in 15th, 3.09 minutes behind the leader, and admits his time on the ride has been a learning curve.
The 27-year-old was in tears and kissed the red jersey as he stood atop the podium.
The three-time Vuelta victor made the decision on Saturday morning to keep racing, something that was in doubt after he took a hard knock and scrapes at the end of the seventh stage. Its special-category finish at the Lagos de Covadonga is considered one of the classic, and most demanding, ascents of the three-week race. "Let's see how long I can hold onto it, but nobody is taking it away from me today".
"I am satisfied because the goal was simply to stay alive", Contador said. "I now have that extra bit of confidence knowing that, today, I was a bit better than my rivals". As for myself - I'm surviving.
"Today was a quieter day, we already knew Alto del Naranco is a climb where it is hard to make gaps".