The Swede had previously been released from the club after sustaining a cruciate knee ligament injury during the Europa League quarter-final.
Zlatan is currently on track for an October return, but will presumably have to train with the first-team before he can be considered match fit by the United boss.
In May, he uploaded a video of himself kicking a ball, just a month after sustaining the career threatening injury. Following his operation, doctors commented on their surprise at the strength and speed of his recover, given the Swede’s age.
Ibrahimovic has since been given full use of United’s Carrington training facilities in order to aide his recovery.
“He is injured and he needs time to recover,” said Mourinho, as reported by the Telegraph. “He is not ready to play tomorrow. It’s not something that’s urgent, it’s not desperate to have it done or not.
“It was very clear by showing what he did last year was not enough for him. He wants more football at the highest level so we are having conversations and discussing the possibility of him staying for the second part of the season.”
Meanwhile, AC Milan reportedly remained interested in taking on the veteran striker, but luckily for the Red Devils, Ibrahimovic has remained in close contact with United throughout his recovery.
This much was self evident, when United’s new No.9 – the number which Ibrahimovic occupied last season – Romelu Lukaku deemed it necessary to seek the Swede’s permission before taking his desired squad number.
United have made their position consistently clear throughout summer, that they would consider extending the Swede’s stay at Old Trafford, depending on how well his recovery went.
Ibrahimovic’s impact last season
Ibrahimovic recorded a goal every 137 minutes in his debut season for United last season. With 28 goals and nine assists, the Swede ended the campaign as United’s top scorer, 17 goals ahead of second place Henrikh Mkhitaryan.
Ibrahimovic was United’s key man up top for Mourinho last season, who rarely deemed it necessary to rest the player.
Lukaku certainly has some big boots to fill this Premier League campaign, with the Swede bagging just over one goal in every two matches in the league.