The England international missed his side's matches against Villarreal and Everton due to the calf problem that he picked up during the home defeat to Aston Villa on September 25.
Maguire was back in the team against Leicester at the King Power Stadium but struggled in Man United's 4-2 defeat, while his recent performances have also been criticised.
According to The Telegraph, the 28-year-old was up to 10 days away from being ready to play when he was selected in the side to face the Foxes.
The report claims that head coach Ole Gunnar Solskjaer decided to include Maguire in his first XI despite the fact that the defender had only started training on the grass one day before the clash.
Meanwhile, Victor Lindelof is a doubt for the clash with Manchester City, with the Sweden international missing out against Atalanta BC on Wednesday due to a problem that he picked up in training on Monday.