Manchester United's new era started on Monday when Ruben Amorim jetted into town to start the daunting task of restoring the club to former glories.

The Portuguese coach bid farewell to Sporting Lisbon in style on Sunday, securing a thrilling 4-2 comeback win at his former club Braga -- an 11th win in 11 league games.

The mood in Manchester has been lifted by three victories in four matches in all competitions since interim boss Ruud van Nistelrooy took over from the sacked Erik ten Hag.

But Amorim will be under no illusions as to the scale of his task at United, who are languishing 13th in the Premier League table after just four wins in 11 matches.

AFP Sport looks at the challenges that Amorim faces.

Change the script

Manchester United have been crowned English champions a record 20 times but they have failed even to compete for the Premier League or Champions League titles since Alex Ferguson stepped down in 2013.

Amorim, a 39-year-old former Portugal international, is United's sixth permanent appointment since the end of Ferguson's trophy-filled 27-year-reign.

David Moyes, Louis van Gaal, Jose Mourinho, Ole Gunnar Solskjaer and Ten Hag have all come and gone, unable to take United back to the top despite lavish spending.

More than £600 million ($772 million) was spent over Ten Hag's five transfer windows on new signings but few have proved value for money.

Despite United's flaws, Amorim will have a greater pool of talent than he did at Sporting, but he will have to work hard to get the most out of an under-performing squad.

He is the first manager appointed since British billionaire Jim Ratcliffe became a minority owner of the club earlier this year, taking control of football operations.

Being Ratcliffe's man should buy him wriggle room and time, but he will know that at a club of the size of United, patience only stretches so far.

"I feel ready for the new challenge," an upbeat Amorim said after his farewell match with Sporting. "I'm not naive, I know that it's going to be very, very different, very tough but I feel that I'm ready."

Style makeover

Two trophies in his only two full seasons were not enough to save Erik ten Hag, whose side never got going in the current campaign.

The Dutchman secured some impressive wins during his tenure against Barcelona, Liverpool and Manchester City but he relied on moments of individual brilliance from an expensively assembled squad rather than imposing a clear style of play.

United frequently appeared chaotic on his watch, combining an alarming fragility with an inability to score goals, and proved infuriatingly inconsistent.

Amorim has earned his ticket to the Premier League after restoring Sporting to the pinnacle of Portuguese football over the past four years.

His preferred 3-4-3 formation could suit the players he will have available at Old Trafford.

But he will have precious little time on the training ground to impose his philosophy as United face a gruelling run of 12 games between November 24 and January 5 following the current international break.

"I know how I'm going to play at the beginning because you have to start with a structure that you know and then you will adapt with the players that you have," Amorim said.

Restore belief among fans

United fans so long used to success have suffered as their team slipped down the pecking order, usurped by Manchester City and Liverpool.

Old Trafford is no longer the fortress it once was. Liverpool and Tottenham cruised to 3-0 victories in September, while Brighton, Bournemouth, Crystal Palace and Fulham won there last season.

Amorim has to energise the Old Trafford crowd and infuse them with the belief that this time things really will get better.

Although United are in the bottom half of the Premier League, they are just four points off the top four, a finishing position that would bring back Champions League football.

Midfielder Casemiro says the players are hungry to learn from their incoming boss.

"We cannot ignore how he has changed Sporting (Lisbon)," he said. "We know that Sporting won many titles, changed the club with titles, with trophies.

"He has already proved that he is a coach that has won a lot."