Mohamed Salah
Salah was restricted to just 19 first-team outings during his season and a half at Chelsea, who loaned the Egyptian out to Fiorentina in February 2015. The former Basel man made an immediate impact in Italy, scoring six times in 16 Serie A games and also finding the net in the Viola’s 3-1 aggregate win against Tottenham in the last 16 of the Europa League.
Diego Forlan
Things just didn’t click for Forlan at Manchester United, who scored only 17 goals in 98 matches during his two and a half years at Old Trafford. The Uruguayan discovered his scoring touch upon moving to La Liga, first with Villarreal and later with Atletico Madrid.
Forlan helped Atleti win the Europa League in 2010, scoring in both legs of the semi-final victory over Liverpool and then notching a brace against Roy Hodgson’s Fulham in the final.
Angel Di Maria
Di Maria was a £59.7m purchase from Real Madrid in 2015, and Manchester United hoped that his signing would kick-start the post-Alex Ferguson era. Yet despite a promising start, the Argentine was a major disappointment at Old Trafford, and United were happy to cash in when PSG came knocking a year later.
Di Maria returned to his former home in 2019 and delivered a man-of-the-match performance as the visitors beat United 2-0 in the first leg of their Champions League last-16 clash. It was the Red Devils who had the last laugh, however: Ole Gunnar Solskjaer’s side stunned the French champions with a 3-1 victory at the Parc des Princes which secured their progression to the quarter-finals.
Robinho
The first big name to arrive at Manchester City following their Abu Dhabi takeover in 2008, Robinho made a fine start to life in the Premier League and finished as his team's top scorer in his debut season. The Brazilian quickly faded thereafter, though, and was sold to Milan in 2010.
The forward never lived up to the potential he showed early on his career, but he was still capable of some magical moments - as demonstrated in a Champions League clash with Arsenal in 2011/12. The two-goal Robinho was brilliant as Milan thrashed Arsene Wenger's side 4-0 in the first leg at San Siro, although they made to sweat after going 3-0 down in the return fixtue.
Christian Panucci
Even Chelsea fans could be forgiven for forgetting that Panucci ever represented their club. The Italian played 10 times for the Blues during a forgettable loan spell in the first half of 2000/01, before seeing out the campaign with Monaco.
The right-back returned to haunt his former side eight years later, though, scoring in a 3-1 defeat of Chelsea in the Champions League group stage. Roma duly finished top of their segment, before losing to Arsenal on penalties in the round of 16.
Gerard Pique
Pique wasn’t an outright flop in English football, but he nevertheless failed to convince Alex Ferguson that he was ready to be a regular first-teamer. The defender returned to Barcelona in 2008 after making just 23 appearances for Manchester United since his arrival at the club four years earlier.
It would be an exaggeration to say that United missed the Spain international given the strength of Rio Ferdinand and Nemanja Vidic’s centre-back partnership, but Pique was excellent in Barcelona’s two Champions League final victories over Ferguson’s side in 2009 and 2011.
Hernan Crespo
Crespo officially spent five seasons on Chelsea’s books, but three of those were spent on loan at San Siro – one with Milan and two with Inter. The Argentine enjoyed a respectable first season at Stamford Bridge with 10 Premier League goals in 19 games, but was nevertheless allowed to join the Rossoneri in 2004/05.
Crespo scored both of Milan’s goals in a 2-0 aggregate victory over Manchester United in the Champions League round of 16, then grabbed a brace to give his side what seemed like an unassailable 3-0 lead at half-time of the final against Liverpool.
Jerome Boateng
A £10.4m signing from Hamburg in 2010, Boateng played 24 matches in his solitary season at Manchester City, before joining Bayern Munich a year later. His debut campaign at the Allianz Arena ended in ignominy, as the Bavarians lost the Champions League final to Chelsea on home soil.
Bayern bounced back the following season, winning the tournament at Wembley after knocking out Arsenal in the round of 16 – although Boateng didn’t feature in the tie. He did, however, help Bayern defeat his former employers in both 2013/14 and 2014/15, scoring a 90th-minute winner in the latter season.
Serge Gnabry
Tottenham were probably the better team in the opening 30 minutes of their Champions League meeting with Bayern Munich this season, but a second-half collapse saw them end the night on the wrong end of an embarrasing 7-2 demolition.
Gnabry was the star of the show, scoring four times in the second half - which is three more goals than he managed during three years in Arsenal's first-team squad. He also made little impression during a loan spell at West Brom, with Tony Pulis infamously declaring that he wasn't of the required level to start for the Baggies.
