Bilbao went close to taking the lead just three minutes into the contest - played at Real Sociedad's Estadio Anoeta due to delays in the construction of Bilbao's new San Mames arena - Andres Fernandes tipping Markel Susaeta's strike onto the post after the winger had beaten the visitors’ offside trap.
That slice of misfortune may have left the hosts feeling aggrieved, but their luck evened out just after the half-hour mark, Osasuna defender Alejandro Arribas turning Susaeta pull back into his own net.
Ander Herrera went close to doubling the lead nine minutes into the second half, before Arribas saw his header drift wide of the post in a rare opportunity for Jose Luis Mendilibar's men.
However, it took a mere two minutes for Luis Garcia Plaza's men to equalise, Angel Lafita meeting Pablo Sarabia's right-wing cross to head home.
Still, Almeria continued to press forward despite that setback, and they rewarded eight minutes before the break as Fernando Soriano converted from close range after Alex Vidal's deflected effort had squirmed into his path.
