Jose Mourinho insists Michael Carrick has an important role to play at Manchester United, despite not having played a minute of competitive football since being named captain. The long-serving 36-year-old was named skipper after all-time top scorer Wayne Rooney's summer departure, but his elevated status has not brought any game time.Carrick has not even made the bench at times in the early weeks of the season, but looks set to finally get some minutes under his belt in the Carabao Cup third round tie against Burton on Wednesday.Last season it was not until United's opening game in this competition that he made his first competitive appearance, before going onto play an important role for the remainder of the campaign - something Mourinho suggests he can do again."(Sergio) Romero played the Europa League final, which was the game of the season for us and he is not playing," the United boss said."Ander Herrera was player of the season and is not starting matches."That's life in big clubs."We gave him a contract because we think he is a good player, an important player, he is just in a team where I think in this moment (Nemanja) Matic and (Marouane) Fellaini are in the best form that I have ever seen them."I never saw Matic or Fellaini play so well, so he is in a team with these two guys playing absolutely phenomenal, so for Carrick and Ander it's just patience because that time will arrive and they will be important players for us for sure."That's a team, that's a squad, we can only play with 11 guys."Carrick, Herrera and Romero are likely to get a chance on Wednesday as David De Gea, Antonio Valencia, Matic and Eric Bailly have been given two days off by Mourinho.The United boss says that quartet are the only players being rested, with Luke Shaw and Scott McTominay hoping to get their first minutes of the season.Changes will be made at Old Trafford but Mourinho will not be taking progress against Sky Bet Championship side Burton for granted as they kick-off their defence of the competition."Oh yes, serious because it's football, it's competition and we take it seriously," the United boss said."Of course David, Bailly aren't playing but if you go to the next round probably these guys play and I give rest to others."Our squad is good but we don't have 30 players, we have what we have and a couple of injuries now with (Paul) Pogba and (Axel) Tuanzebe, so we need some of the players that played today to play and we need some to be on the bench."We need to have a strong team. I know the quality of the Championship and I know if we don't take it seriously, we are going to lose."