Replaced by Paulo Dybala in the 55th minute in Sunday’s 1-0 win over AC MIlan, Ronaldo didn’t look best pleased as he made his way off the pitch.
After high-fiving Dybala — who then scored the winning goal — the 34-year-old Ronaldo appeared to direct some words at Sarri before heading down the tunnel.
“If it’s true that he left before the end it is a problem to be resolved with his teammates,” Sarri told reporters.
Ronaldo had been substituted a few days earlier against Lokomotiv Moscow in a Champions League group stage game — Juventus went on to score a late winner after he left the pitch.
Ronaldo has now been substituted as many times this season as he was throughout the entire 2018/19 campaign.
According to Sarri, the former Sporting Lisbon, Real Madrid and Manchester United forward — who has scored just six goals in 14 appearances this season — has been struggling with injuries.
“In the last month he has had discomfort in his knee and this is a little problem for him.
“The important thing is that he made himself available. If he gets angry when he comes out this is part of the game.
“It’s only natural a player is going to be irritated about leaving the pitch, especially when he worked so hard to be there.
“All players who are trying to give their best will have at least five minutes of being annoyed when they are substituted, but a coach would in general be much more worried if he didn’t seem upset.”
Juventus had struggled to break down a miserly AC Milan side before Ronaldo’s departure as it searched to return to the top of the Italian Serie A table.
But thanks to Dybala’s third league goal this season, Juventus remain unbeaten, and one point ahead of Inter Milan, while AC Milan drop to 14th place.