Eight players who went from being flops to world beaters: Gnabry, Salah, Forlan…

If it isn’t frustrating enough to see an exciting signing come in and underperform, it’s even worse when they leave and fulfil their potential elsewhere.

Football is full of comeback stories and miraculous turnarounds, whether it be on the pitch or even in a player's career.

It's quite common to see a player flop when joining a new club full of expectation and responsibility, but not all of them can come back from such lows.

However, these eight players were not only able to revive their careers, but also managed to transform into some of the world's best after making a move away.

Serge Gnabry

Serge Gnabry during his West Brom loan stint

If we rewind to the 2015/16 season, Arsenal sent a struggling Serge Gnabry out on loan to West Brom, hoping a stint away from the club would reinvigorate the promising German star.

However, Baggies manager Tony Pulis only trusted Gnabry with one start during his time in the Midlands, and Gnabry was once even subbed off during an under-21 game.

On his return to Arsenal, it seemed clear to all that Gnabry's time at the top level of football was over…

But in a crazy turn of events, six years on Gnabry is now a consistent starter for Bayern Munich, winning the club's Player of the Season award in 2019 as well as the Champions League and seven domestic titles.

Only 26 years old, Gnabry still has time to improve, and his career has never looked so promising. Not bad for a player deemed not good enough for West Brom.

When Pulis was later questioned about Gnabry's improvement at Bayern Munich, the English manager said: "You could knock me over with a feather. I'm amazed. We had him at West Brom, we took him on loan, and we could never get him fit."

Mohamed Salah

Mohamed Salah during his time at Chelsea

From a Chelsea flop to one of the world's best players, Mohamed Salah's comeback story is one of the best out there.

After making a name for himself at Basel, Chelsea took a gamble on the Egyptian star in 2014, signing him for £11million.

However, after scoring just twice for the Blues in 13 appearances, it seemed Chelsea's gamble had failed, and Salah was subsequently loaned out to Fiorentina and then Roma.

He began to find his feet in Rome and his 29 goals in 65 appearances caught the eye of Liverpool, who were willing to look past his Chelsea stint and spend £36million on his signature.

It's fair to say that Liverpool's investment has since been repaid several times over by Salah. Now coined Liverpool's 'Egyptian King', he has gone on to score 115 goals in 174 appearances, all while firing the Reds to Premier League and Champions League glory.

It's always a bit unfair to suggest Chelsea should have kept hold of him, but they'll surely have a tinge of regret as they watch him fulfil his potential for their Premier League rivals.

Matteo Guendouzi

Matteo Guendouzi in action for Marseille

Earlier this week, Marseille manager Jorge Sampaoli suggested that Guendouzi is on his way to "becoming the world's best midfielder".

The 22-year-old French midfielder has set Ligue 1 alight since joining Marseille on loan from Arsenal for the 2021/22 season.

However, that was probably the last thing Gunners boss Mikel Arteta expected from Guendouzi after he dropped the midfielder from his side.

He reportedly fell out of favour due to concerns over his attitude, but even when given a string of games for Arsenal, Guendouzi looked nothing like the player that is now the heartbeat of an impressive Marseille side.

But even if Arteta wanted to swallow his pride and welcome Guendouzi back to the Emirates, he's been denied the chance to do so by Marseille. They have confirmed they'll sign him permanently in the close season after triggering a clause in the loan agreement.

At just 22, Guendouzi could yet live up to the high expectations Sampaoli has placed on him, and become the latest Arsenal player to thrive after leaving the club.

Diego Forlan

Diego Forlan, Manchester United

Forlan's time at Manchester United can only be classified as one thing - a disaster.

The Old Trafford faithful may still sing his name to this day due to his heroics against arch-rivals Liverpool, but that came after the Uruguayan took 27 games to open his goalscoring account.

After joining the Red Devils in 2002, Forlan stuck around for just two seasons before moving to Villarreal in 2004. After scoring just 10 goals in 63 appearances, United fans breathed a collective sigh of relief as he headed for the exit.

But to their amazement - and frankly everyone else's too - Forlan set La Liga alight, scoring 54 goals in 106 appearances.

What's more, Forlan then joined Atletico Madrid in 2007 and went on to score a further 74 goals in 134 games.

He even started performing for his national side too, top-scoring in the 2010 World Cup with five goals for his native Uruguay.

Memphis Depay

Memphis Depay only managed two goals for Manchester United

When Manchester United beat PSG to the signing of Memphis Depay for £25million back in 2015, big things were expected of the talented Dutchman.

Reunited with former Netherlands boss Louis van Gaal, Memphis being handed the esteemed No. 7 jersey tells you all you need to know about the expectation placed on his shoulders.

However, after scoring 40 goals from out wide for PSV in just 90 appearances, Depay managed a measly two in the colours of United. That's despite spending two seasons and making 33 appearances for the Red Devils.

Wayne Rooney has since told a comedic anecdote about Depay's time in the United Under-23s.

"He came on at Stoke away and messed up for their goal," Rooney begins.

"So, Louis van Gaal made him play for the reserves the next day. I said, 'look, it's a bit difficult [for you]. Just don't come in with all your fancy stuff'.

"And he turned up for the reserve game in his Rolls-Royce, wearing a leather jacket and a cowboy hat. And I just thought, 'What's the point?'".

With his career at a standstill at United, the club cut their losses and sold him to Lyon for £17million in 2017. Memphis enjoyed his football far more in France, scoring 63 goals in 139 appearances, earning a move to Barcelona in 2021.

To frustrate United fans even more, Memphis has made a strong start to life in Spain, scoring 10 goals in 21 appearances.

Shkodran Mustafi

Shkodran Mustafi in action for Arsenal, 2018

After impressing at youth level in Germany, Everton were quick to snap up Mustafi and assign him to their academy squad.

Seen as a young centre-back with plenty of potential, Mustafi's future at Goodison Park looked bright, and the German seemed comfortable in Merseyside, suggesting it "feels like home" in an interview.

However, despite spending three years at the club, including two with the senior squad, Mustafi failed to make a single professional appearance for the Toffees.

He completed a free transfer to Sampdoria in 2012 and just two years later he found himself wearing a World Cup winners medal around his neck.

His impressive World Cup performances immediately caught the eye of clubs around Europe and Mustafi then enjoyed successful stints at both Valencia and Arsenal, where he won two FA Cups.

Andy Robertson

Andy Robertson in action for Hull City

Liverpool's acquisition of Robertson for just £8million back in 2017 remains one of the greatest bargains in Premier League history.

But what's even more surprising, is that Hull fans weren't too disheartened to see the back of their Scottish left-back when Liverpool came calling.

Robertson had spent three years with the Tigers since joining them from Dundee United in 2014, but in that time he had been relegated twice and was often the culprit when the East Yorkshire side conceded.

Therefore, despite Jurgen Klopp looking to rebuild the Reds, it was seen as something of a left-field move for Liverpool to sign him in 2017.

However, since arriving at Anfield, Robertson has transformed into one of the world's best full-backs, breaking records for assists alongside team-mate Trent Alexander-Arnold and winning both the Premier League and Champions League in his five years at the club.

Gennaro Gattuso

Gennaro Gattuso in action for AC Milan in 2006

A two-time Champions League and Serie A winner, Gattusso is part of a long list of legendary Italian players.

However, his career wasn't always as glistening as it was during his time at AC Milan. In fact, Gattuso endured a dreadful stint at Rangers in the 1997/98 season before his big break came in Italy.

He joined the Scottish club after impressing for Serie B side Perugia during his teenage years, but newly appointed manager Dick Advocaat played him out of position at right-back and ended up limiting Gattuso to a place on the bench.

After spending just a season at Ibrox, Gattuso was sold to Serie A side Salernitana for £4million.

Back in his native Italy, Gattuso began to fulfil his potential, and he quickly earned himself a move to AC Milan, where he went on to spend 13 years of his career, making over 300 appearances.

Gattuso also was capped 73 times for Italy, and was involved in the World Cup-winning 2006 squad. It's fair to say he didn't let his time at Rangers define him…

READ MORE: Seven relegation-threatened players who deserve another shot in the Premier League

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