Reports suggest Latics recently snubbed an approach from the Championship club to take the 21-year-old on loan. And Martinez says the youngster is key to his plans, telling the Daily Mirror: "I expect Callum to play a big part with us this season."
McManaman and 19-year-old Arsenal loanee Ryo Miyaichi came on as replacements for defensive duo Gary Caldwell and Emmerson Boyce with just less than 15 minutes to go against Fulham at the weekend. The young attacking duo impressed Martinez despite the 2-1 defeat, putting them in a strong position to be handed starts against Sam Allardyce's West Ham in the Capital One Cup on Tuesday night.
"That's a real positive for us to have a couple of youngsters of that quality," said the manager. "So I was really pleased with that and I think it shows the competition we've got now for places."