Philippe Coutinho has admitted that his performances for Barcelona have fallen short of expectations, but has called for patience as the club continues to go through a "renewal process".
Signed from Liverpool in 2018 in a deal potentially worth €160 million (£142m), the Brazil international has not had the desired impact at Camp Nou.
Coutinho, who has scored 15 goals and provided nine assists in 60 La Liga appearances, spent last season on loan at Bayern Munich and won the treble under Hansi Flick.
He returned to Barca for 2020-21 and has been directly involved in four goals in eight league outings, but the Catalans' inconsistent form has not helped him to thrive.
Coutinho started Saturday's shock 2-1 loss at Cadiz but managed only one shot and one key pass before being substituted for Ousmane Dembele at half-time.
With Dembele having suffered another hamstring injury, Coutinho is likely to start on Tuesday against Juventus as Barca look to secure top spot in their Champions League group.
While he accepts Barca are negotiating their way through a transition period and that his own form has not been as hoped, Coutinho says he has become mentally and physically more robust.
"I know my form hasn't been what everyone expected," the 28-year-old said ahead of Juve's arrival at Camp Nou. "Barca have the attention of everyone and what I can say is that I've worked a lot more mentally to be well, and nowadays, I consider myself stronger in that sense.
"We're in a renewal process. We've changed coach, the players... all this forms part of the renewal process. You have to be patient and do everything to make it that things work as soon as possible.
"Whenever you lose an important game, the atmosphere is one of frustration. But I see everyone wanting to change this moment we're going through. Mentally, I'm stronger than before and the team looks eager to change this.
"I started to work in a different way. It was necessary to have more strength. And mentally, it's the same. There are things that are making me stronger and, physically and mentally, I'm doing a better job."
Barca face Juventus knowing they will finish top of the group if they avoid losing by three goals or more, or by a two-goal margin other than 2-0.