Ibrahimovic made his long-awaited return from a cruciate knee ligament injury in the 4-1 win over Newcastle United last Saturday, coming off the bench for the final 13 minutes with his side cruising to victory.
The Swede came on for the final 16 minutes against Basel in the Champions League on Wednesday as United seek to carefully manage his return after such a serious injury with Mourinho confirming the club will adopt the same approach this weekend.
"We managed to give Zlatan 15/20 mintues in both matches, he needs more of that, so hopefully tomorrow we play him again," Mourinho told MUTV.
He continued: "He's not ready, step by step, minute by minute, match by match. He's not a player that you play only if the team is losing or only if the team is winning. He's a player that's easy to bring in to the game, so normally he's going to have these periods of 15-20 [minutes] and, one day, we will feel that he's physically ready [to start]."
Paul Pogba meanwhile has also recently returned from a three-month lay-off, scoring and providing an assist in his first game back against Newcastle before starting again midweek in Switzerland. In both those appearances, the France international was taken off before the 70-minute mark and Mourinho says the club will continue to carefully manage his game time in the coming weeks.
"Paul is still on this process where he cannot reach the fatigue limit, he cannot go more than 65/70 minutes and with so many games consecutively, we need to protect such an important player for us."
Elsewhere, central defensive options Jones and Bailly are still unavailable – despite Mourinho's hopes earlier this week the latter would recover in time.
Jones returned from England duty with a knock that has ruled him out of United's last two matches – much to the ire of his manager. Bailly has also been sidelined since returning from the international break with an unspecified knock but Mourinho felt he "had a chance" of returning for Saturday when speaking to the press midweek.
The Ivory Coast international will not be contention, however. "Bailly and Jones - they are out, but we are okay because we have Smalling, Rojo and Lindelof."
Marcos Rojo played the full 90 minutes against Basel in his first game back since suffering a season-ending knee injury last April. The Argentina international impressed on his return to action but Mourinho may opt to name him on the bench on Saturday, leaving him with the starting options of Chris Smalling and Victor Lindelof.
"He [Rojo] played very well [against FC Basel]. We have to see how he is today. The injury is gone, but after playing his first match back, maybe he feels it a little bit."