The 29-year old midfielder suffered a broken bone in his foot in a 3-0 win over Chelsea in the Champions League and will be out of action for close to three weeks.
It was all Barca after that, and Leo Messi doubled their lead on the half hour and but for visiting keeper, Kepa Arrizabalaga and the woodwork the game would have been over by halftime.
A minute before the break the home side hit the woodwork once more when Paulinho was played through on goal, but with just the keeper to beat, he shot against the post.
Just four days after an encounter with Chelsea that was more exacting than the 3-0 scoreline suggested, the intensity understandably dropped in the second half, but Valverde's men were able to keep Athletic at arm's length to ensure they head into the worldwide break in buoyant mood.
Barcelona's Argentinian forward Lionel Messi celebrates scoring his team's third goal during the UEFA Champions League round of sixteen second leg football match between FC Barcelona and Chelsea FC at the Camp Nou stadium in Barcelona on March 14, 2018. He almost had another in the 80th minute before goalkeeper Kepa caught the deflection.
In the 33rd minute, Ousmane Dembele picked out Messi, who had been left unmarked lurking on the edge of the penalty area, and he punished the visitors by drilling the ball into the bottom corner. He cut the ball back for Coutinho this time and the Brazilian unleashed a fierce shot that came back off the crossbar.
Neymar's father: "My son has a future at PSG"
But with Brazil competing at the World Cup in June, Neymar is racing to be fully fit. Neymar has a future at Paris Saint-Germain, according to his agent and father.
- Athletic Bilbao have lost 61 away games against Barcelona in LaLiga; more than against any other team (P87 W17 D9 L61).
Barcelona maintained their unbeaten La Liga record this season as they cruised to victory over Athletic Bilbao.
Barcelona boss Ernesto Valverde has insisted he is not afraid of the pressures he may find himself under as the season reaches its finale, with his side still fighting on all three fronts. Athletic are also the team Alcacer scored his first goal as a Barcelona player in February 2017.
Messi has scored at least a goal in his last six matches.
- Messi has scored 17 goals in his 19 games at the Camp Nou against Athletic in all competitions. Maybe his role isn't as attacking as it was at Sevilla, but players do move around.