Zlatan Ibrahimovic would have to accept “that’s life” if José Mourinho selects Romelu Lukaku and Marcus Rashford before him when he is available again for Manchester United.

On Thursday Ibrahimovic re-signed on a one-year deal but is still recovering from a serious knee injury and Mourinho believes the 35-year-old will not be ready for action until next year. The manager is insistent that, if Ibrahimovic proves deserving of first-choice status, he will receive it. By the same token the striker will have to settle for a substitute’s berth if Lukaku and Rashford are on form.

“Zlatan knows me,” the manager said. “And he knows that I play the players that are the best for the team. I always did that in my life so, if he comes here and he proves that he is the best, he plays. If the other ones don’t give him a chance to prove that, that’s life. But I try always to be honest with my players and with my team. I try. Maybe sometimes I do not do the correct things. But I always try.

“Zlatan is going to arrive into a made team. He is going to arrive mid-season with the team playing in a certain way and with players having what I call the functional links in the dynamic of the team. We are going to be a better squad and I give you just one example – if we play Stoke and two days later we play against Burton and I want to give a rest to my two strikers, who do I play against Burton? I have to play Rashford or Lukaku. I don’t have another one to play so I cannot give rest to my players. So we need a striker and we have one just around the corner that belongs to our family, that likes to be with us and play for us.

“He is one more striker, he is one more experienced player, one more player that can play No9 or No10, that can play in a double striker [system]. There are lots of matches to play. If we progress in the Champions League and one of the two cups we are going to be in the position where we couldn’t do it only with Lukaku and Rashford, especially if I play both together. So if I need a striker, probably in January I would be knocking on [executive vice-chairman] Ed Woodward’s door and [now] I don’t need to. I have one of the best in the world.”

Mourinho praised Henrikh Mkhitaryan’s start and admitted the forward’s progress could have been quicker last season if they had understood each other better. Mkhitaryan started United’s 4-0 wins over West Ham and Swansea City in the No10 berth, impressing in each. Last season Mkhitaryan did not make his full debut until Manchester City’s visit on 10 September and was replaced at half-time.

Asked about the 28-year-old’s form now Mourinho said: “He understands me and I understand him. Beginning of [last] season, if he had understood me better he would start better. If I had understood him better, probably I would have helped him in a faster way than I did. But we spent a lot of time together, learning each other. I know him well. He knows me well. The second part was good for him. With his talent, this season [will be] even better.”

Mourinho offered a similar analysis of Anthony Martial, who has scored in both league wins as a substitute. “When you are blessed with talent, you have to fulfil and explore it. You cannot be happy with just glimpses. That I am not going to change. I want more and more and more. He has all the qualities for that. He understands me better too.

“Our personal relationship is good. I don’t think player-manager relationship is fundamental but it is an added good thing to have a good relation. I hope he will be better this season than last.”

On Saturday Leicester City travel to Old Trafford for the late kick-off. The 2016 champions have started the season well, losing narrowly to Arsenal at the Emirates and beating Brighton at home. Mourinho said: “It is the same team as they were two seasons ago [when they were champions]. After what they did, [we could probably] could feel that they would not be champions a second consecutive season. Are they going to be champions again? Honestly, I don’t think so. All the other teams are not all going to fail.”

Get (free) transfer notifications for all the clubs in the Premier League, La Liga, Bundesliga, Ligue 1 and the Bundesliga