The French centre-forward appeared destined to leave Bramall Lane this summer, following a series of controversial incidents off the pitch and United’s relegation from the Premier League.
But Jokanovic’s appointment could prove to be a turning point for Mousset, with senior figures behind the scenes expecting the former Yugoslavia international to offer a clean slate in return for a more professional approach away from the game.
Despite frustrating Jokanovic’s predecessor Chris Wilder with his conduct during the past two seasons, it was significant that Mousset started United’s first friendly of the summer earlier this month.
Cutting a noticeably trimmer figure than towards the end of Wilder’s reign, the former AFC Bournemouth striker repaid the Serb’s faith by scoring the second of the three goals netted en route to a comfortable victory over Gibraltarians Europa Point.
Unless injury or illness intervene - a spokesperson for United confirmed over the weekend that United have suffered a Covid-19 scare since returning to England - Mousset is likely to feature again when United continue their preparations for the new campaign with a visit to Doncaster Rovers on July 28.
Although his long-term future in South Yorkshire must remain in doubt, Mousset, who was linked with a move to Russia during the winter transfer window, is regarded as potentially the most explosive member of their attack by long-serving members of United’s coaching staff.
However, his fitness and conditioning levels have often left much to be desired since joining United for £10m two summers ago. Many of those who have tracked his progress since believe those explain why he has also proved susceptible to injuries.
A toe problem, sustained during pre-season, saw him miss much of the previous campaign. He was also clearly out of shape when he did return to action, making little impression before suffering another knock.
However like Wilder - until his patience began to wane during the closing stages of his reign - Jokanovic is ready to persevere because he recognises how effective a fit and focused Mousset could be. Particularly in the Championship. After appointing Jokanovic, who has led both Watford and Fulham to promotion from the division, United will be expected to push for an immediate return to the top-flight next term.
Mousset has apparently been drinking in the Last Chance Saloon at United for so long now, he probably has his own pewter pint pot and seat at the bar. But it is not difficult to fathom why people are prepared to keep persevering with him.
Talent guarantees forgiveness in football. And Mousset has lashings of it. His polite and friendly personality also helps; something Wilder alluded to soon after Mousset crashed his Lamborghini sports car early in the New Year.
“He’s a great lad,” Wilder said. “We all love him, everyone does. He’s always got a smile on his face and is good to have around the place.
“Yes, he can frustrate you. He frustrates the hell out of me at times. But it’s only because you know just how good he could be if everything clicks into place.”
Jokanovic appears to have reached the same conclusion. However, with United almost certain to trim their attacking options before the end of the transfer window, any false steps or wrong moves during pre-season could signal the end of Mousset’s time with them.
Marco Cesarini and Rafa Cristobal, United’s new heads of medical and performance respectively, are likely to be central characters in the next phase of Mousset’s story. His susceptibility to minor knocks, which then develop into something more serious, points to a deeper, underlying problem.
Plenty of sportspeople also balloon in weight during periods of inactivity. But the speed with which Mousset’s waistline appears to grow whenever he is sidelined is also symptomatic of a lifestyle which isn’t as spartan as it should be. No one is asking Mousset to behave like a monk. But certain sacrifices have to be made.
If Cesarini and Cristobal can persuade him to make the necessary changes, they will have repaid their annual salaries before the campaign has even started.
Anyone who witnessed Mousset terrorising Manchester City’s defence during a superb first-half display at the Etihad two seasons ago will be aware of what a devastating weapon he can be. Jokanovic, who admits to having reviewed hours of footage of United games before officially taking up his position at the beginning of the month, is also bound to have noticed his searing pace.
Rhian Brewster is quick and, at 21 years of age, has time on his side. But Mousset, four years Brewster’s senior, is positively turbocharged when on form and in good nick. After scoring five times in 10 appearances soon after completing a £10m move from AFC Bournemouth, Mousset is capable of finding the back of the net at the highest level.
So he can certainly do the same in the second tier. It therefore makes economic as well as footballing sense to keep hammering away.
While Cesarini and Cristobal try to improve Mousset physically, Jokanovic’s job will be the work on him psychologically should he decide to grant the former Le Havre prospect one final opportunity to prove he has what it takes.
If Jokanovic can succeed, and Mousset fulfils his side of the bargain then, rather than being a waste, the fee United paid to acquire him will look like a snip.