The manager did not reveal exactly what Rashford suffered ahead of their Sevilla Europa League quarter-final match.
Manchester United manager Erik ten Hag has blamed compressed fixtures after his star player Marcus Rashford suffered an injury.
Rashford had to be stretchered off with 10 minutes remaining as the Red Devils battled – and defeated – Everton to go third.
"I don't know [about Marcus]. It is like this when you have to play so many games in short notice, especially when the schedule is this tight. Players can't recover, and you run the risk that players can get injured. You have to be aware of that," the Dutchman told the club’s website.
"You can't say [exactly what has happened], even when you speak to him. We have to wait until tomorrow, or the day after tomorrow, then we will see what the diagnosis is.
16:45 - 08.04.2023
PREMIER LEAGUE Manchester United suffer Rashford setback in win over Everton
The England forward limped off late in the second half for what could be a groin injury.
"We have to protect our players - everyone wants the best players on the pitch. Everyone wants to see great, entertaining football like you see today, but then you need your best players."
Rashford’s injury – which came in his 350th appearance for the club– came as United welcomed Christian Eriksen back into action. The Dane started on the bench as Ten Hag made three changes following Wednesday’s win over Brentford.
Meanwhile, this was the first defeat in five Premier League games for Everton and left them outside the relegation zone on goal difference.
United have won 39 league games against Everton, the joint most victories one side has against another in the competition's history (also 39 wins for the Red Devils against Spurs).
On the other hand, Everton have lost three games against United in a single campaign for just a third time (1993-94, 2015-16 & 2022-23), with this being the 18th season, the two sides have met at least three times.