Team Sky's climbers put on an attacking show at Clasica San Sebastian as the race came down to a sprint finish behind lone victor Luis Leon Sanchez.
Sergio Henao, Rigoberto Urán and Richie Porte were all on the offensive and finished in a select group of favourites which fought it out for second place.
The trio pushed hard in the closing stages to keep the pace high to haul back the lone escapee, demonstrating their form ahead of Saturday's Vuelta a Espana.
Sanchez (Rabobank) delighted his home crowd after a gutsy move with nine kilometres to go saw him maintain a slender advantage all the way to the beachfront finish.
An elite group formed behind, but with no team possessing a clear numerical advantage a tactical battle ensued as the Spaniard, also a victor in 2010, profited up ahead.
A bunch kick at the line saw Simon Gerrans (Orica-GreenEDGE) and Gianni Meersman (Lotto-Belisol) round out the podium positions.
The race burst into life over the top of the famed Alto de Jaizkibel as the bunch split into two on the descent, further attacks on the final climb leaving around 30 riders to combine as the terrain flattened out on the run-in.
The 234km classic got under way with a competing mix of one-day specialists and riders gearing up for the Vuelta.
Adrian Palomares (Andalucia) and Francisco Aramendia (Caja Rural) opened things up and combined to go clear, pulling out a gap of 10:46 before teams began to push on behind.
The pace ramped up and the break were dragged back first time over the Jaizkibel, the catch causing a second wave of attacks with Nario Quintana (Movistar), Eros Capecchi (Liquigas-Cannondale) and Team Sky's Michael Rogers among those to chance their arm.
With that move deemed too dangerous, one man who was able to get clear was Tiziano Dall’Antonia (Liquigas-Cannondale), Tomasz Marczynski (Vacansoleil-DCM) bridging across on the Alto de Arkale first time around.
With the main group splitting on the descent off the Jaizkibel five riders emerged with a gap, Henao among those out front.
The climber set a strong pace the final time over the Arkale as five became three in the move, the Colombian joined by Rafael Valls (Vacansoleil-DCM) and Rafal Majka (Saxo Bank-Tinkoff Bank).
Behind in the bunch an attack from Joaquim Rodriguez (Katusha) proved to be the catalyst for an action-packed run for home which ultimately saw Sanchez prevail.
After the race Sports Director Sean Yates praised the efforts of the riders and explained how the day panned out.
“The plan was to try and win the race and get a top result,” he said. “We knew it was open and there was no one team or individual who would control things. The idea was to save energy for as long as possible and that two-man breakaway was ideal for us as we didn’t have to chase it. Then it was about being in the moves and Sergio did well to get in a good move which was closed down.
“Richie was in the chase group behind and Rigoberto managed to stay with them when Rodriguez opened up the gas on the climb. Richie was a bit boxed when Luis Leon went. He tried to go afterwards but Sanchez is such a strong rider. Rigoberto also tried to get across so it wasn’t for a lack of trying today. They all tried their hardest. One once guy is out there it’s always harder to get someone else up the road. No one wants to miss another move.
“After his effort Rigoberto ran out of legs at the finish but the way he and all the guys rode is really encouraging heading into the Vuelta. It was a good effort. Xabi did well early on and the whole team played their roles. The end result was just lacking but not the performance.”
Yates was particularly proud to see the riders take the race on in an attempt to get a top result.
He added: “I’d rather the guys really try and go out there and make a race of it. That’s what Luis Leon did and he reaped the benefits. We’ve won a fair amount of races this year but today we tried and didn’t reap the benefits. You could see we were trying as we had good legs and we got in the mix. Nothing ventured nothing gained.”