England boss Gareth Southgate said Marcus Rashford is "clearly not at his best" after dropping the out-of-form Manchester United forward.
The 24-year-old has registered just six goal involvements in 19 Premier League appearances in a frustrating campaign for the Red Devils, and will not feature in England's upcoming home friendlies against Switzerland and Ivory Coast.
Rashford has earned 46 caps for his country and scored 12 international goals, his last strike coming against Romania in a pre-Euro 2020 friendly last June.
But the forward has made just 10 league starts for United this season, leading to suggestions he could seek to leave Old Trafford in the summer, ahead of the World Cup at the end of the year.
"He is in the same position as everyone else, whether they are in the squad or not," Southgate said. "They've all got to play well towards the end of this season and, in particular, at the beginning of next season.
"It is a difficult time for him, he's clearly not at his best, but there is plenty of time. We know what Marcus can bring, and hopefully he can rediscover the form he's capable of."
Rashford was not the only United attacker to be left out of Southgate-s squad, with Jadon Sancho remaining absent despite registering five goal involvements in his last six Premier League appearances, having recorded just one in his first 18.
Southgate acknowledged Sancho's club form has improved after the winger made a slow start to his United career, stating his absence was due to the competition provided by England's other attackers.
"You just have to look at the other attacking players in the squad: Bukayo Saka, Emile Smith Rowe, Phil Foden," the England boss said. "Jadon's performances have improved at Manchester United, but it is an area where we have big competition for places."
Southgate also left Manchester City right-back Kyle Walker out of his latest group but was keen to emphasise the upcoming games represent an opportunity to look at other right-back options.
"I had a chat with Kyle; we felt this was an opportunity to have a look at the two younger full-backs," Southgate said.
"We know all there is to know about Kyle; he's a very important player, and he'll be back with us in June [for Nations League matches].
"We are very happy with what he's done. He's been a huge part of the progress we've made with this team, and you can see in the biggest matches with Manchester City this year, he's still been a key player for them.
"These young full-backs [Trent Alexander-Arnold and Reece James] are exciting."
The England boss also hit back at suggestions Manchester United defender Harry Maguire could have missed out on the squad, highlighting his importance to England despite there having been recent criticism of his displays at club level.
"There wasn't a chance we weren't going to call him up," Southgate said. "He's one of our best centre-backs."