Manchester United centre-backs Victor Lindelof (29) and Lisandro Martinez (26) will be out for at least a month with muscle injuries, the Premier League club said on Tuesday.
Sweden captain Lindelof went off in the second half of Saturday's draw with Brentford with a hamstring problem.
Martinez replaced him in the 69th minute, making his first appearance since early February after recovering from a knee injury.
However, the Argentina international then suffered a calf strain in training and will not be available for the next games.
United, who are sixth in the table on 48 points with nine league games remaining, face Chelsea away on Thursday.
