Casemiro is set to miss a key stretch of Manchester United’s season after Erik ten Hag revealed the midfielder will be sidelined with a hamstring injury until after Christmas. The 31-year-old midfielder has struggled for form and fitness in his second season since his eye-catching switch to Old Trafford from Real Madrid. Casemiro sustained an ankle injury on Brazil duty last month and returned against Newcastle last Wednesday, only to be taken off at half-time of the 3-0 Carabao Cup defeat. United confirmed the Brazil international had sustained a hamstring issue that would keep him out for “several weeks”, but Ten Hag has now suggested the midfielder may struggle to play again this year. Left-backs Luke Shaw and Tyrell Malacia may return in the coming weeks but Casemiro and Lisandro Martinez, who is out with a foot injury, are set to miss the 10 matches before Christmas. “I have some time schedules, yeah,” Ten Hag said. “But it’s always difficult to project that because there can always be setbacks during the rehab period. “I’m always a little bit holding back on such issues. I expect some back but, for instance, Casemiro and Martinez are really strong injuries and I don’t expect them back before Christmas.” Among the 10 matches Casemiro is expected to miss before Christmas is Wednesday’s key Champions League group game at Copenhagen. The 31-year-old was suspended for the reverse fixture two weeks ago, when Andre Onana’s stoppage-time penalty save and Harry Maguire’s header secured a 1-0 win at Old Trafford. The latter has enjoyed a resurgence of late but brain injury charity Headway questioned the decision to allow him to continue playing after a head collision in Saturday’s 1-0 win at Fulham. Maguire completed the match and is in United’s 23-man squad to face the Danish champions. “So, we did all the protocols during and after the game, so he is ready to play,” Ten Hag said. “There is not any indication (of concussion). “He was fine in the game so no problems. He played a very good game.” United’s squad also includes Victor Lindelof and Marcus Rashford, who missed the trip to Craven Cottage through illness and a leg issue respectively. “100 per cent (fit),” the United boss said. “Rashy missed one game out. A small knock but he’s back.” United will hope the pair’s return can help continue their revival after making hard work of beating Copenhagen on home soil, having lost their Group A openers against Bayern Munich and Galatasaray. “They played a very decent game and I thought we didn’t play a good game,” Ten Hag added. “But, still, we won. I think it was a deserved win but we have to do things better. “We are aware of that because you have to lift the performance if you want to get the result in.” Read More The Fulham star set to show Man United the midfield move they should have made Manchester United confirm Casemiro injury blow ahead of crucial run Erik ten Hag says ‘only a matter of time’ until Manchester United form improves Manchester United ‘have got to move on’ from humbling derby experience Erik ten Hag reveals Casemiro injury latest ahead of Manchester derby Man City v Young Boys LIVE: Champions League result and reaction