Aspas scores late as Girona's winless run goes on
Girona, the surprise third-place finisher last season, dominated possession in the early stages before taking the lead in the 38th minute when Yangel Herrera rose high to head in Daley Blind's cross.
Celta responded well but initially struggled to test Paulo Gazzaniga in its search for an equaliser, with Girona offering little in terms of threat at the other end.
The hosts eventually found a way through in the 81st minute. Williot Swedberg laid the ball off to substitute Aspas, who made no mistake with a composed finish into the bottom corner.
Girona boss Michel said believes injuries to key players are a concern for his side, after Oriol Romeu and Blind limped off.
Romeu was forced off in the 14th minute, while defender Blind had to be replaced early in the second half, with both players doubtful for Girona's UEFA Champions League clash with Feyenoord this week.
Girona is embarking on the first European campaign of its 94-year history, and the head coach believes his players are feeling the effects of the increased workload.
"We don't have experience of playing every three days. If Romeu is out for several weeks in midfield, we will be left with a weak team. We'll see what the tests tell us.
"We are inexperienced and, every day, we are looking for solutions to the new reality. The players have raised their voices and Girona cannot manage like the big teams.
"We lose two players? Well, that's the way it is. We have to train as little as possible and analyse a lot from the office."