McManaman is preparing to return to the DW Stadium at the start of next month after spending the last two months on loan with Championship side Blackpool.
Martinez has been watching his progress at Bloomfield Road and believes the young striker can make an immediate impact when he returns to Wigan in the new year, and is already planning to unleash him on Swindon in the FA Cup third round.
Martinez told the Wigan Evening Post: "It's been great to see Callum enjoying his football and growing while at Blackpool. It was important for him to get regular minutes under his belt, and we've all been admiring his progress from a distance.
"He'll be returning to our club as a more mature and confident player, ready to fight for his place in the first team.
"And we're all looking forward to seeing him back here in the first week of January.
"His time with Blackpool has been exactly what he needed at this stage of his career. His quality has really come to the fore - and that was the whole reason for the exercise."