Vitor Roque and Chimy Avila struck for the visitors, which also saw Natan sent off in injury-time. Osasuna scored through Lucas Torro.
Afterwards, Pellegrini recognised the significance of the win at an in-form Osasuna.
The result:
"It was a very eventful match , the intensity was high and at the end it got complicated and tangled up. Johnny (Cardoso) had a blow to the head , but he continued playing and now we'll see what it is, but I don't think it's anything serious. Bartra came out tired after so long without playing but we held on..."
Vitor Roque's goal:
"I'm very happy for him because he had been getting opportunities and he wasn't scoring. Then he felt contractures in both calves and we didn't want to risk a tear. He couldn't keep running and we didn't want to force him. I don't think he has an injury, it's a question of fatigue. The whole team responded according to the needs. We came to look for points in a difficult place, and in the end we got all three."
Natan's sending off:
"A play in the middle of the pitch, I haven't seen the play yet, but we were left with one less player at the end and we can't have him against Atlético de Madrid. But these are occasional things that happen and I'm very sorry that it happened."
Losses: "I said that we were coming off two tough defeats, but they were two 1-0 away losses from corners and a penalty. The team had dropped a bit but I felt that we were neither in crisis nor lacking confidence. Far from it. Winning today was very important to get back on track and I think that, despite the losses, we didn't just hang around those who were missing but those who were there responded in a very difficult match against a good team."
Abde's substitution:
"Like all players who go to their national teams, he accumulates minutes. He has played almost all of them with us, now we have to play on Thursday and Sunday, there are many injured... It is good to go in doses. We did it with Lo Celso in the Conference League. It was risky to put him in as a starter."
Chimy Ávila's goal:
"It's important for all forwards to score goals, he was attentive to that rebound. Hopefully this will give him confidence and he will maintain a high performance. He couldn't train normally in recent days, he had a contracture and wasn't at 100%. Sometimes he has to focus a little more on the game."