Antonio Conte has stressed Gary Cahill should not be held responsible for Ryan Mason being forced to retire prematurely due to injury.
Mason suffered a skull fracture after clashing heads with Cahill in an aerial challenge during a game between Chelsea and Hull City at Stamford Bridge in January 2017.
The one-cap England international had hoped to be able to return to the pitch but Mason confirmed this week he has called time on his career after taking medical advice.
Chelsea face Mason's former club Hull in the fifth round of the FA Cup on Friday and Conte believes the midfielder's retirement ought to be considered an unfortunate side-effect of football.
"For sure, this is a question for Gary," Conte said when asked how Cahill had responded to Mason's retirement. "But, at the same time, I think it's okay.
"When you play and your behaviour is always with great honesty. We are talking about a top player, no? For his commitment, his behaviour during, before and after the game. This type of situation can happen.
"I was a player and I understand it. I broke my leg. My team-mate broke my leg when I was 16 - and risked my whole career. But it was an unlucky situation.
"I repeat: Gary is a fantastic guy, a fantastic person. He must be okay because it's not his fault."
Mason's family are Chelsea supporters and the former player has an open invitation to return to Stamford Bridge, although he is not expected to be present for the game against Hull.
Conte confirmed Chelsea captain Cahill, benched for the 3-0 Premier League defeat of bottom side West Brom on Monday, is in line to return to the side.
"Yes, he's in contention for tomorrow's game," Conte said.
"I think I have to make the best decisions for the team. I try to be honest before with myself, and then with the players. Every choice I make is for the best of the team. I will continue to do this for the rest of the season. As I always did.
"I think every player wants to play every game. I repeat: Hull City don't remember him... or don't give him bad feelings, you understand? It's not right [to implicate Cahill for Mason's injury] - I repeat - not right.
"I must be honest, I didn't speak with him. I think that, if I have to go to speak with him, it means there is a problem. I don't see a problem. Football is this. Sometimes it can happen, this type of situation. The most important thing is there is not the will to do this."
With Chelsea taking on Hull on Friday, they have an extra day of recovery compared to Barcelona - who play Eibar on Saturday - ahead of Tuesday's Champions League last-16 meeting at Stamford Bridge.
But with Chelsea facing Manchester City and Manchester United in the Premier League before March's second leg against the Catalan giants, Conte believes any advantage could be cancelled out.
"I think to play on Friday is good for us," Conte added. "Three days to try and prepare the game against Barcelona.
"At the same time, between these games, we have two strong games in the league: Manchester United and Manchester City, both away.
"If we were lucky to play on Friday, we were very unlucky to have this schedule between the two Barcelona games - United, City. This schedule is not very interesting for us. Maybe it is for someone else.
"I hope no [FA Cup] replay, no. We had one against Norwich [City], but I hope to try and win this game and go through without a replay."
