Blaise Matuidi has described Cristiano Ronaldo as a "monster" after seeing just how hard his new Juventus team-mate works in training.
Ronaldo has yet to score for his new club since his stunning €112million move from Real Madrid, drawing a blank in his opening three games in Serie A.
However, despite the lack of goals, the Portugal international has still made a positive impression at the Italian champions, particularly with his desire to keep on improving.
Matuidi - who scored the decisive goal for Juve in Saturday's 2-1 win at Parma - is in no doubt the Portuguese is the best in the world right now, placing him above long-time rival Lionel Messi.
"He's the best player in the world, and it's a lot of fun playing with him," the France international told Telefoot.
"At work, he's a monster. He arrives first and leaves last. He's working, he's working ... I've never seen that and I understand better now why he's won the Ballon d'Or five times."
Ronaldo was unable to steer his country to FIFA World Cup glory in Russia this year but was quick to congratulate Matuidi, who helped Les Bleus secure the trophy with victory over Croatia in the final.
"Did he congratulate me? Of course. It was his first words when he saw me, in French," Matuidi revealed.
The former Paris Saint-Germain player also offered an insight into how his life had altered since winning the World Cup.
"People's eyes have changed. Many people congratulate us on a daily basis," Matuidi said.
"One evening, I was organising a reception at home and one of the neighbours came to complain about the noise. However, when she saw me, she burst into tears. Only football can produce emotions like that."