Zinedine Zidane's appointment as Real Madrid coach has changed the entire mentality of the club, according to Alessandro Del Piero.
Zidane took over as Madrid boss in early January after Rafael Benitez was sacked just seven months into the job.
The Frenchman has guided Madrid back into contention for the La Liga title, while also seeing them through to the Champions League semi-finals.
Del Piero - who was team-mates with Zidane at Juventus - believes the 43-year-old has done wonders for the club since taking over.
"All of what he's worked for and how he has prepared himself as a trainer is incredible," Del Piero said.
"It is so difficult to do what he has done in such little time.
"He has changed the mentality of Madrid. Both of the team and the fans. I send him my best for La Liga and Champions League this season."
A third-consecutive loss for Barca has seen Luis Enrique's men have their lead atop the league standings cut to just one point with five games left to play.
"I am a little bit surprised, it's an incredible situation," Del Piero added.
"If anyone told me two weeks ago that Barca would [drop] this many points or be out of the Champions League I would have told you it was impossible.
"But I think that is what makes this sport so beautiful. It's a challenge for the teams and it will help people follow La Liga more in the final games to see what happens."