Athletic threatened to make a fast start in Edin Terzić’s first game at the helm, with Odysseas Vlachodimos busy in the early stages to keep out Benat Gerenabarrena and Inaki Williams from the edge of the area.
However, the match soon turned in Sevilla’s favour when Yuri Berchiche was sent for an early bath for bringing down Miguel Sierra just outside the box.
The visitors took advantage of having the extra man almost immediately, with some shaky passing from Athletic around the back capitalised by Oso, who passed into an unguarded net.
There were some encouraging signs from the hosts towards the end of the first half, as despite going down to 10 men, they managed to conjure up some decent chances through Oihan Sancet, who struck just wide.
He then set up Williams, who saw his deflected effort saved by Vlachodimos, ensuring that Sevilla would register their first half-time lead in 18 LaLiga away games.
Luis García bravely made three changes at the break to try and extend his team’s advantage, and two of them repaid his faith immediately in the second half, as Isaac Romero fed Chidera Ejuke out wide, and he drove into the box before delightfully chipping Unai Simon.
It quickly got from bad to worse for Athletic with another defensive mistake costing them dearly, as Jesús Areso was easily dispossessed by Oso, who added to his first-half goal with an assist by teeing up Romero to find the far corner.
Yet, the hosts did manage a consolation goal through an unlikely source in Aitor Paredes, with the centre-back lashing home after the ball fell to him from a corner, but the damage was already done.
On top of the defeat, Athletic have now kept just one clean sheet in their last 29 matches, and Terzic still has plenty of work to do on today’s evidence, with a daunting trip to champions Barcelona next on the agenda.
Meanwhile, the Sevillistas can brag about being top of the table in its early stages, with Garcia recording only his second away victory since taking the job in late March.
Flashscore Man of the Match: Aitor Paredes (Athletic Club)