Douglas Costa admitted he had doubts about Cristiano Ronaldo after he joined Juventus but the superstar "won everyone over very quickly" at the Italian champion.
Ronaldo swapped Real Madrid for Juve in a stunning €112million deal at the start of the season and the five-time Ballon d'Or justified the investment as he led the Serie A holder into the Champions League quarterfinals.
The 34-year-old forward scored a record-equalling eighth Champions League hat-trick to see off Atletico Madrid 3-0 in Turin on Tuesday and 3-2 on aggregate.
Ronaldo has netted 24 goals in all competitions in his first season with Juve – 19 of those coming in Serie A – and team-mate Costa heaped praise on the Portugal international following his initial concerns.
"When he arrived. I thought 'the best player in the world has joined, right?'" Costa told YouTube channel De Sola. "As soon as he arrived, the club improved in every aspect. His contribution has been noticeable.
"He scores goals every week, he’s brought more fans to the stadium and we hope to win things with him so we make history with him by our side.
"He's a stand-up guy, he's hard-working and he's always with us. If he doesn't talk to me, who does he talk to? We only talk in Portuguese.
"Believe it or not but when Cristiano Ronaldo's arrival was being talked about, I asked 'what will the dressing room be like?'
"We all have to love each other as team-mates because we're all looking for a place in the team, but Cristiano won everyone over very quickly.
"He's a simple, hardworking guy who likes to win. Juventus were looking for a player with his mentality, so he's given us a lot."
Juve – which will face Ajax in the Champions League quarters – travels to Genoa on Sunday.