Spaniard De la Cruz had attacked from the day’s escape group to claim the victory ahead of Dries Devenyns (IAM), and more than make up on his overall time deficit to race leader Quintana. It is de la Cruz’s first victory since turning professional in 2010.
Behind the break, the GC riders were happy to finish in a group despite the climb to the finish line on Alto del Naranco.
Quintana is now second overall, 22 seconds adrift of de la Cruz. Quintana’s Movistar team-mate Alejandro Valverde is third at 41 seconds, with Chris Froome (Sky) in fourth at 49 seconds.
The day’s original break formed after 15km, with 12 riders managing to escape the grip of the peloton: Jan Bakelants (Ag2r), Pello Bilbao (Caja Rural), Simon Clarke (Cannondale-Drapac), David de la Cruz (Etixx-QuickStep), Dries Devenyns (IAM Cycling), Thomas De Gendt (Lotto-Soudal), Mathias Frank (IAM Cycling), Alexandre Geniez (FDJ), Bartosz Huzarski (Bora-Argon 18), Moreno Moser (Cannondale-Drapac), Luis Leon Sanchez (Astana) and Dylan Teuns (BMC).
The dozen riders kept together until the final 40km, with De Gendt launching a move. He was reeled back in, with Devenyns then launching a new attack followed by Bakelants and Teuns.
Obviously unhappy with the split, Sanchez dragged the rest of the escapees back up to the lead trio with 15km to go. At that point, the escapees had four and a half minutes on the peloton.
Over the top of the penultimate climb of the day – Alto de la Manzaneda – Devenyns went off the front again, this time with de la Cruz for company.
The pair quickly opened up a gap on the descent, with de la Cruz attacking within the final kilometre to take the victory and with it the coveted red jersey of overall race leader.
The Vuelta continues on Monday with stage 10, a 188.7km trip from Lugones to Lagos de Covadonga which finishes with a long climb, highlighted as one of the key points of the race.
With the Vuelta’s first rest day on Tuesday, the GC riders will put on more of a show – de la Cruz is not expected to retain the overall lead.
Vuelta a España 2016, stage nine: Cistierna to Oviedo Alto del Naranco, 164.5km
1. David de la Cruz (Esp) Etixx-QuickStep in 3-47-56
2. Dries Devenyns (Bel) IAM Cycling at 27 secs
3. Moreno Moser (Ita) Cannondale-Drapac at 33 secs
4. Luis Leon Sanchez (Esp) Astana at 51 secs
5. Mathias Frank (Sui) IAM Cycling at same time
6. Alexandre Geniez (Fra) FDJ at 53 secs
7. Bartosz Huzarski (Pol) Bora-Argon 18 at 58 secs
8. Thomas De Gendt (Bel) Lotto-Soudal at 1-04
9. Pello Bilbao (Esp) Caja Rural-Seguros RGA at same time
10. Dylan Teuns (Bel) Cannondale-Drapac at 1-10
General classification after stage nine
1. David de la Cruz (Esp) Etixx-QuickStep in 33-46-24
2. Nairo Quintana (Col) Movistar at 22 secs
3. Alejandro Valverde (Esp) Movistar at 41 secs
4. Christopher Froome (GBr) Team Sky at 49 secs
5. Johan Esteban Chaves (Col) Orica-BikeExchange in 1-19
6. Leopold Konig (Cze) Team Sky at 1-38
7. Alberto Contador (Esp) Tinkoff at 2-01
8. John Darwin Atapuma (Col) BMC Racing at 2-06
9. Gianluca Brambilla (Ita) Etixx-QuickStep at 2-07
10. Samuel Sanchez (Esp) BMC Racing at 2-08