If José Mourinho leads Manchester United to victory in Sunday’s EFL Cup final against Southampton the tonic will be twofold. Having been sacked from his previous post by Chelsea, Mourinho will reaffirm himself as a serial winner and attain the ideal launchpad for his greater ambition of claiming the club’s 21st league title and making United a Champions League force again.

The EFL Cup is the least valued of the three domestic competitions but, as with Chelsea in the 2004-05 season, winning it may go some way to convincing Mourinho’s squad that the first championship of the post-Sir Alex Ferguson era is possible under him.

“When you have a taste of good things, you want to repeat it,” the Portuguese said. “When you get used to winning, when you don’t win, you miss it. You don’t accept not winning and you are always chasing for more success, so I think it’s a good thing for the players if we manage to win another trophy.

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“We all know the history of this club, that football is changing, that it’s much harder than it was before, but last season was a very difficult season for the club and players, but together with their manager [Louis van Gaal], they managed to win a trophy [the FA Cup]. It was a good taste for them, so we have to try.”

Ander Herrera, who was an unused substitute at Wembley against Crystal Palace, concurs with his manager. “We want to win every trophy because we want to respect our history and our fans,” the midfielder said. “This club is about titles, we don’t select which competitions we go for, we go into all of them to try to win. We know it is not easy but we try.”

United’s holy grail is being crowned champions again. Twenty of United’s 44 major honours have been titles but barring a miracle it will not occur this season, of course. United are 12 points behind Chelsea with only 13 matches remaining. But the longer the season goes on the more Mourinho is transforming United into the relentless proposition all his finest sides have been.

A major factor in this is the belief any contest can be pulled out of the fire. On Sunday United conceded first at Blackburn Rovers, then calmly went about winning the FA Cup fifth round tie 2-1. “Everyone who watches our games realises very quickly that a big team is playing because we control all the games or most of them,” Herrera said. “When Blackburn scored, we didn’t go crazy, we kept playing, moving the ball from side to side, creating chances. We have a lot of confidence in ourselves and we are showing just how difficult it is to beat us. I cannot say it is impossible to beat us but it is difficult because we are very compact, we all attack, we create chances.”

Chelsea’s defeat of Liverpool in the 2005 League Cup final provided a vital shot in the arm for Mourinho’s Stamford Bridge project: a trophy glut ensued as his side won consecutive Premier League titles, the FA Cup and a second League Cup in his three full seasons.

One gauge of where United are under Mourinho is found in the league performance so far. The 48 points accumulated after 25 matches is his lowest in English football. It compares poorly to the opening seasons of his two tenures in west London. At the 25-game mark in 2004-05 Chelsea had 64 points. In 2013-14 the count was 56.

Yet a glass half-full reading of this is that guiding United to Sunday’s final is a particular positive given the relative weakness of the side he inherited compared with those at Chelsea.

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In the summer of 2004 Claudio Ranieri’s side had just finished second and reached the European Cup semi-finals, while in 2013 the team Rafael Benítez left to Mourinho were third.

Last year United finished fifth with a squad that still required a sizeable rebuild due to a lack of quality and depth in central defence, midfield and attack. In his first close season Mourinho addressed this by buying Eric Bailly, Paul Pogba, Henrikh Mkhitaryan and Zlatan Ibrahimovic before integrating all of them into the side. This has taken time and the squad is not yet as strong as he wishes it to be, with another striker and a left-back, at least, due to be targeted in the summer.

Mourinho does, though, have what each of his three champion Chelsea sides possessed: a talismanic centre-forward. In the 2004-05 and 2005-06 vintages this was Didier Drogba; in the 14-15 team it was Diego Costa. For United this is Ibrahimovic, with Mourinho saying any serious layoff for the 24-goal man would be a “disaster”.

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Herrera also underlined how vital the Swede can be against Southampton and to United going forward. “He is the target for us. He has great height, he holds the ball up and he has the fantasy to resolve the play like he did. It was fantastic to get him because sometimes the opponents are scared of him and the rest of us take advantage of that. We get more space, more second ball. We have one of the best in the world. We are so lucky because we have him and hopefully we can enjoy him for a long time.”

On Sunday Mourinho has the chance to achieve what none of his predecessors have in United’s 139-year history: claim a major honour in his first season as manager. But it is what it can do for the long-term success of the club that is more significant: deepen the belief of his players and help propel United on to being champions of England again, and challenging seriously for a fourth European Cup.