Casemiro has added to Manchester Uniteds injury crisis after manager Erik ten Hag said the Brazil midfielder will be sidelined until Christmas at the earliest with a hamstring injury.

United had been waiting to assess the full extent of the injury sustained by the 31-year-old during last Wednesdays

Carabao Cup defeat against Newcastle at Old Trafford.- Stream on ESPN+: LaLiga, Bundesliga, more (U.S.)

Speaking in Denmark ahead of Uniteds Champions League Group A clash against FC Copenhagen, Ten Hag said that Casemiro will now join fellow long-term absentee

Lisandro Martínez (broken metatarsal) in the treatment room."I expect some [injured players] back but Casemiro and Martinez, they are really strong injuries and I dont expect them back before Christmas," Ten Hag said. "Its several weeks [for Casemiro]."

Casemiro was substituted at halftime of Manchester Uniteds chastening Carabao Cup defeat to Newcastle.

(Photo by Michael Regan/Getty ImagesLeft-backs Luke Shaw and Tyrell Malacia have both been sidelined since the early weeks of the season and remain unavailable, while teenage midfielder

Kobbie Mainoo misses the trip to Copenhagen due to injury.However, Ten Hag said that both Harry Maguire

and Marcus Rashford are fit to face the Danish champions.Maguire played the full 90 minutes of Saturdays win at

Fulham despite going down twice for treatment due to dizziness, while Rashford missed the game after failing a pre-match fitness test.

"We did all the [concussion] protocols during and after the game, so he [Maguire] is ready to play," the Dutch coach said. "There is not any indication [of concussion].

"He [Maguire] was fine in the game, so no problems. He played a very good game. Rashford missed one game out, a small knock but hes back, 100%."