Frank Lampard insists he retains huge belief in Mason Mount, despite substituting the Chelsea midfielder at half-time in the FA Cup quarter-final at Leicester City.

Lampard was disgruntled with the Blues’ first-half display at the King Power Stadium, with Mount and fellow youngsters Reece James and Billy Gilmour hooked.

Mount’s replacement Ross Barkley netted the winning goal to book a semi-final showdown against Manchester United.

Nevertheless, speaking ahead of Wednesday’s London derby at West Ham, Lampard insisted the standing of a player he took on loan to Derby County last season before overseeing a breakthrough at Premier League and international level is not at all diminished.

“I rely on Mason a lot. I did at Derby, I do at Chelsea,” Lampard said, with Mount’s 44 appearances in all competitions this season acting to back up his point.

“He brings so much to the team in his work ethic and the way he can start up a press in midfield. And then obviously his quality on the ball, which is only going to get better and it’s already at a really high level.

“Mason wouldn’t have been happy going off at half-time. I know that because, a bit like myself, I know that when he’s not playing he’s not happy and if he comes off he won’t be happy.

“It was certainly a moment where he should be not happy that evening and then straight back to it afterwards because he knows how much I trust in him.

“He works brilliantly every day. And when I talk about Mason, I’m talking about Reece and Billy in the same breath.

“There’ll be no problem at all with Mason. I had to make a decision and it doesn’t affect my thinking for West Ham or going forwards.”

A match against West Ham is one to relish for Mount, given it brings him into direct competition with childhood friend Declan Rice – something Lampard acknowledges can be a motivating factor.

“I think it spurs you on more if you have a personal relationship in either way – whether they’re your best friend or you don’t like each other,” he said.

“I always think the result of that is not concrete either. You can have your best games in those circumstances and also become overly focused on that relationship and have not-so-good games.

“They’re two very good young players. The only thing I ask of Mason going into this one is that he texts him tonight and smiles at him with a tongue or whatever it is, but if and when they go up against each other he has to try and beat him in every individual battle that he possibly can.

“And, sensing Declan Rice’s character, I think they’ll both be like-minded on that one.”

Rice and Mount fell foul of UK lockdown restrictions when they were seen sharing a kickabout earlier in the coronavirus crisis.

Chelsea reminded the 21-year-old of his responsibilities at the time and Lampard was quick to draw a line under the incident.

“I saw Mason in a couple of places compared to players who went out partying and stayed up all night and did different things,” he added.

“I’m not wanting to angle on that, but what I want to say is Mason was very innocently and naively and wrongly – he held his hands up to that at the time – kicking a ball about. That’s so typical of Mason, how he lives his life.

“I had the shortest ever conversation with Mason. He was pretty apologetic that he got it wrong straight away and we moved on.”