Because it is Jack Grealish, it is tempting to call it a hangover. After the glorious madness of last season, when he and his Manchester City teammates pulled off the ultimate treble, there was always the possibility he would feel a little bit discombobulated when he got back to work. He agrees that it has been the case, even if he cannot quite find the right words to describe it.

Grealish has endured a difficult season so far, which is one of the reasons he is so keen to put on a show for England in the friendly against Australia at Wembley on Friday night. And in the Euro 2024 qualifier against Italy next Tuesday, also at the national stadium.

But there is a simpler explanation for Grealish’s false start; why he has come to view the past few weeks as a second attempt at a pre-season: injury. Namely, the dead leg he suffered in City’s win at Sheffield United on 27 August. Grealish had started in four of the club’s opening five games, including the European Super Cup win over Sevilla, when he scored his kick in the penalty shootout.

Everything would grind to a halt in the wake of an innocuous-looking coming together with the Sheffield United striker Oli McBurnie.

“You might all laugh at me now because it was a dead leg but it was the worst dead leg I’ve ever had in my life … I can’t even explain the pain,” Grealish says. Suddenly he is off, going into graphic detail, talking about how bad dead legs have haematomas that are 6cm in length; this one was 20cm. “Our doc at City, who has worked at Milan and everything, said it’s the worst dead leg he’d ever seen – by a mile,” Grealish says.

The 28-year-old mentions the horrific kidney injury he suffered at his previous club, Aston Villa, in 2017. In fairness, that was worse; he needed life-saving surgery. But he will never forget the pain post-Bramall Lane, which started to grip him on the coach back to Manchester. “I genuinely could not walk when we got to the training ground at City,” he says. “I was on crutches for a few days.”

The next two weeks saw him grit his teeth. A lot. “With a dead leg, you need to keep it moving – you more or less have to try and hurt it to make it better, to separate all the blood,” Grealish says. And for three and a half weeks after, as he struggled to bend his leg, he could not do one cardiovascular session.

Grealish was back as a substitute for City in the Premier League against Nottingham Forest on 23 September. He has been on the bench for them in their subsequent fixtures in the competition, used briefly at Wolves, unused at Arsenal. He did start the Carabao Cup defeat at Newcastle and the Champions League win at RB Leipzig but, although the injury feels OK, he says he is not 100% fit. “I am just trying to catch up and do my own little mini pre-season,” he says.

Jack Grealish (right) trains with England teammate Fikayo Tomori after overcoming a painful leg injury. Photograph: Eddie Keogh/The FA/Getty Images

Grealish’s thought processes during the actual pre-season and the early weeks of this campaign are worth a listen. “I am not saying it is hard to get motivated [after winning the treble] – you can’t say that,” he says. “But when you’ve done it, it’s kind of like: ‘What now?’

“It would have been nice to do something that we have never done – maybe win all four [trophies], put the Carabao Cup in there as well. But we are out of the Carabao Cup. Then it was maybe try to do an invincible [league] season but we got beaten by Wolves.

“I have never been off the back of a season like the one I had last time. I felt I was really on top of my game in the second half of it, I was playing in every big game and we had the perfect end to it. You come back in pre-season and it’s a bit like … not ‘What now?’ actually. But do you know what I mean? So, in that sense, yeah, it was a bit difficult.”

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Gareth Southgate has suggested that he will try to get minutes into some of his non-first-choice selections against Australia – and Grealish is probably in that category, just behind his City teammate Phil Foden for the slot on the left wing. There is also Marcus Rashford, James Maddison and Eberechi Eze; Bukayo Saka and Jarrod Bowen on the other flank, the out-of-favour Raheem Sterling, too. Eze and Saka are missing through injury.

“The quality we have in the attacking areas, especially on the wing, is maybe the best in world football,” Grealish says. “If you put six or seven of us wingers in that same category, it is probably the best any international team or club team have got. There are six games left between now and the Euros [next summer] and it’s massive for everyone. If we get a chance in the next couple of games, we’ll all be looking to take it.”

Grealish versus Foden is an interesting dynamic; good friends who appear forever in each other’s way. Pep Guardiola has started them in the same City team only three times this season, albeit Grealish did have his spell out.

Grealish, though, is positively evangelical when he talks about the team spirit for club and country, noting with the latter that injured players such as Luke Shaw and Saka have still reported to St George’s Park just to hang out. Grealish did the same when he missed the September fixtures because of his injury, staying over for a night.

“We feel like there’s unfinished business with the Euros,” Grealish says, with a nod to the penalty shootout defeat against Italy in the final of the previous tournament. “Without putting too much pressure on ourselves, this is the one we are really looking at to go in and win. We do feel this is our time, especially with the players we have.”