As Manchester United head to Sunderland on Saturday, two key players will be missing from the lineup: Casemiro and Benjamin Šeško. Šeško was an expected absentee, as the striker was removed from proceedings at half time against Liverpool last Sunday. Speaking on Friday, interim manager Michael Carrick said the Slovenia international has been dealing with a nagging shin injury and was likely to miss out on the weekend’s match. Casemiro, however, was a shock absentee for the trip to the Stadium of Light. The Brazilian star midfielder has reportedly suffered a “minor injury”, but he is anticipated to be fit enough to return to action next week for his final match at Old Trafford as a Red Devil. With the two stars sidelined, Carrick was forced to make some major changes to the lineup . Joshua Zirkzee replaces United ’s leading goal scorer at the No. 9 for his first start of the Carrick era, meanwhile Mason Mount earns his first start in the midfield under Carrick, flanked by Amad and Matheus Cunha.…