"I rely on Mason a lot. I did at Derby, I do at Chelsea,"
"He brings so much to the team in his work ethic and the way he can start the press in midfield and obviously his quality on the ball which is only going to get better and it’s already at a high level.
"Mason wouldn’t have been happy to come off at half time. I know that from myself and if there’s one comparison I can make is that I know if he’s not playing, then he won’t be happy.
"He should not be happy that evening, but then straight back to it afterwards because he knows how much I trust in him and he works brilliantly every day.
"When I say Mason, I mean Billy [Gilmour] and Reece [James] in the same breath because they show a similar attitude. There will be no problem with Mason because it was a one-off game, I had to make a decision and it doesn’t affect my thinking for West Ham or going forwards.
I think the first two games after the restart, which Mason played 90 minutes in both, at Aston Villa he was incredibly lively with the ball, gave them a lot of problems going forward, probably unfortunate not to score or have an assist.
"The work ethic and quality that he showed against Manchester City was also incredible and the performance we showed as a team was also really good.
"So, he had two big performances in a week and then in the Leicester game; Mason didn’t really have a bad performance, it was a performance in line with the team and my choices to change were about the players that I could bring into that performance rather than the players who were on the pitch, because I could have made a lot of changes in that game.
"It was more about whether I could bring some energy into the team."
Mount and his Childhood friend Declan Rice was found to be breaching lockdown rules in April but the 42-year Old confirmed that he reprimanded the young englishman and he was apologetic
“I had the shortest word possible,"
"Mason was very innocently, and, as you say, naively wrong at the time and he very quickly held his hands up to that.
"But he was kicking a ball about and that’s so typical of Mason and how he lives his life. So I had the shortest ever conversation with Mason. He was pretty apologetic and said he got it wrong straight away and we moved on.
"In that sort of circumstance [of Rice and Mount's friendship ahead of kick-off] but you can also become overly focused on that relationship and have a not so good game. They are two very good players.
"But there is only one thing I will ask of Mason – and from my point of view that is obviously all I care about going into this one. He texts him tonight, he smiles at him in the tunnel or whatever it is, but if and when they go up against each other he has try to beat him in every individual battle that he possibly can.
"Sensing Rice's character, I am sensing they will both be like-minded on that one. We will see."