The substitute tucked a low finish past Aitor Fernandez at the near post in the closing stages to keep the Blaugrana on the march to the title.

It delivered crucial relief for Xavi's side after they had largely failed to make the most out of an extra body against the visitor, after Jorge Herrando's 26th-minute red card.

The win moves Barca onto 82 points and potentially just a couple of games away from clinching a first LaLiga title since the 2018-2019 campaign.

An otherwise tepid game that had mustered little in the way of excitement burst into life shortly before the half-hour mark when Osasuna debutant Herrando brought down Pedri as the last man.

Referee Javier Iglesias brandished a straight red to end the 22-year-old's involvement, before Raphinha brushed the crossbar with the subsequent 30-yard free-kick.

Barca still looked below their best however and were forced to withdraw a limping Gavi before the break, though Ronald Araujo went close with a low header from a set-piece.

With its man advantage, the host stepped up its attempts to find an opener after the interval, with Ousmane Dembele firing wide at close range just after the hour mark.

Robert Lewandowski looked to have finally made the breakthrough with less than a quarter-hour left, only for Ferran Torres to be flagged offside as the host feared it would have to settle for a share of the spoils.

But Alba was there to net the winner in the 85th minute, slotting a neat strike between Fernandez and the post to send the home crowd into raptures.