With the international break now over, United are expected to finalise agreements with both defender Maguire and midfielder Mainoo.
Transfer expert Fabrizio Romano stated: "Manchester United, with Harry Maguire and Kobbie Mainoo returning from the national team, are now prepared to accelerate and formally close both new contracts for the players before the World Cup.
"This is the mission, before the end of the season, sign everything.
"With Kobbie Mainoo 2031 and with Harry Maguire to extend for one season until 2027, plus an option for one more year. The negotiation is already very advanced with Kobbie Mainoo, it is almost done with Harry Maguire, who will sign soon.
"Man United plan to announce everything before the end of the season. This is the club's wish, now working with the player's camp, everything is advancing very well."