Manchester United want to sign Gareth Bale from Real Madrid and are not put off by the forward’s injury problems because they believe they would be able to improve his condition.

Bale has missed 40 of Real’s last 60 matches because of injury. He has not played since late September and is expected to be out for a further month and a half after suffering a thigh problem last week when he was nearing a return from calf trouble.

That was the Wales international’s 19th injury since he joined Real in September 2013 for a then world record £85m but it is understood this is not a concern for United. José Mourinho has previously tried to bring Bale to Old Trafford and remains keen to do so, though any bid is expected next summer rather than in January.

United are encouraged by Bale’s better appearance record when at Tottenham Hotspur and believe they could return him to a similar level of games. He played 52 matches in the season before his move to Madrid, 48 the campaign before and 44 in 2010-11. Bale earns about £350,000 a week after tax and is contracted until 2022. He has a €1bn (£890m) buyout clause but given his injury issues Real would demand considerably less if they wanted to sell him.

United’s injury problems are easing, with Paul Pogba, Zlatan Ibrahimovic and Marcos Rojo available for Saturday’s home game against Newcastle United. Mourinho picked out Pogba’s absence as a particular hardship for the team.

Pogba pulled a hamstring during the 3-0 Champions League win over Basel on 12 September. United were unbeaten at that point but surrendered that record when losing 2-1 at Huddersfield a month later. They also lost at Chelsea in the last match before the international break. Ibrahimovic and Rojo have been out since April with knee injuries..

Mourinho said: “Now I can speak because Paul is back but you can clearly see Manchester United this season before Paul’s injury and after Paul’s injury. There are qualities in our football that influence our approach in matches, with Pogba and without Pogba, that’s as simple as that.”

Ibrahimovic ended last season as United’s top scorer with 28 goals, despite his campaign ending early.

Mourinho said: “Zlatan last season we played with him every minute almost until he was injured. This season we learn how to play without him but he’s a very important player. We welcome him back.

“He has an incredible personality to fight such an important injury. We were all saying in 2017 he will be back but one thing is 31 December 2017 and another thing is mid-November. He was as an injured player the same super professional he is when he’s fit.

“So fantastic work – same as Marcos, who had a serious injury too, a big surgery. He played with the young boys [the reserves] on Wednesday and is fine, is confident, is also ready. Paul is obviously not the same dimension, was not a surgical situation but was also bad and all three are back.”

Of the 36-year-old Ibrahimovic, Mourinho added: “You cannot expect him to play 90 minutes or consecutive matches like he did all his career. Now he needs time to be back for his level, his fitness, his confidence, everything, his sharpness, but by the clinical point of view it is fantastic to be ready.”

United are in second place, eight points behind Manchester City. Mourinho pointed to the two derby games as vital if they are to catch City.

“I am confident that tomorrow we can win against Newcastle, and that is the way we have to look at it: to play every match thinking we can win and to think we play against City in two matches where we can interfere with the situation,” he said. “All the other matches Manchester City plays we cannot interfere with. We can watch it, we can agree with some referee decisions in their matches, yes or no. But we can’t interfere.”