Thomas believes Carrick's absence may give Fellaini an opportunity to shine.
"The midfield is crucial and we must win each game in that area," the Welshman told ManUtd.com. "With Carrick likely to be out, it'll be interesting to see who plays in midfield.
"Personally, I think it might give Fellaini the opportunity to come in and do well," Thomas added. "When he was at Everton he effectively cost United the league in 2012 with his performance at Old Trafford [4-4 draw]. He can provide the aggression in midfield that we need."
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