Barcelona coach Hansi Flick praised Polish goalkeeper Wojciech Szczesny's contribution to the team as the leaders prepare for the visit of mid-table Osasuna in LaLiga on Saturday.
Szczesny has become a key player for Barca after coming out of retirement in October to join the club, who were seeking a replacement after Marc-Andre ter Stegen's long-term injury.
At Benfica in the Champions League on Wednesday, the 34-year-old was central to 10-man Barcelona gaining a 1-0 advantage in the first leg of their last-16 tie.
"He is fantastic. The other players were defending 10 against 11, and he helped us a lot. That is his job. We cannot hide it. He does his job very well, and that is why he is now the No 1," Flick told reporters on Friday.
"When you watch players in training, you get a feeling. I discuss it with my staff, I see how the players work and what level they can reach.
"It was clear to everyone that Szczesny could reach this level. We all knew it. I make the decisions, but I talk with my coaching staff."
Flick is wary of Osasuna, who were the first team to beat Barcelona in LaLiga this season with a 4-2 win in September.
"It was different, we played away ... Tomorrow, we have to field the best possible team. I think our performance level is different now. I am optimistic about tomorrow’s match," he said.
Barca are a point ahead of Atletico Madrid and three in front of Real Madrid before 11th-placed Osasuna visit.
"It is always good to be positive and to maintain a positive image at all times. If you approach things from a negative perspective, trying to avoid mistakes, I don’t think that’s good. We can defend well as a team.
"It will be a tough game - I always say the same. They played very well there, pressed us well, also in one-on-one situations. It was difficult for us to get out of their press. We will try to be prepared."