Aston Villa's permanent deal for Philippe Coutinho is significant for Steven Gerrard's side, but it also represents another landmark for Barcelona's regrettable recent transfer windows.
The Brazil international has put pen to paper on a four-year deal with the Premier League club, after they agreed a £17m fee with Barca. That's a loss of more than £100m for the La Liga club, who paid a nine-figure sum to bring him to Camp Nou from Liverpool in January 2018.
Coutinho isn't the only signing from the 2017-18 campaign who didn't have the desired impact, though. Ernesto Valverde's side brought in seven players on permanent deals, but Coutinho's permanent exit means just one remains - and he too could be gone before long. Here, Mirror Football takes a look at all seven
Marlon
Brazilian wonderkid Marlon joined Barcelona from Fluminense, having spent the previous season on loan at Camp Nou. The young defender had an inauspicious start, forgetting his passport for a Champions League trip, but impressed enough on loan to step up from the B team to the seniors.
Upon joining permanently, he was sent out on loan to Nice, but the switch ended prematurely and he moved to Sassuolo in the summer of 2018. He did not play a competitive game for Barca in the interim.
The Catalan club had a buy-back option on the centre-back, who turned 27 in February. However, they did not exercise the option and he moved to Shakhtar Donetsk at the end of the 2021 season.
Gerard Deulofeu
One player who Barcelona did use a buy-back option on was Deulofeu. A product of La Masia, the creative forward returned to Camp Nou after impressing in England for Everton.
The Spain international was given a few opportunities by Valverde, scoring twice in his second spell. However, when Coutinho arrived in January, Deulofeu was sent out on loan to Watford.
Watford made the loan move permanent after he helped them reach the 2018 FA Cup final. He left for Udinese after the Hornets' 2020 relegation, though, and has top-scored this season for the Italian club.
Nelson Semedo
Barcelona faced plenty of competition for Semedo in 2017. Manchester United were also keen, with manager Jose Mourinho looking to add a younger competitor for Antonio Valencia, but it was Barca who won the race.
The £26m signing got plenty of game-time in his first season, making more than 30 appearances. It wasn't enough for a spot in Portugal's World Cup squad, though, with Cedric Soares and Ricardo Pereira preferred by international boss Fernando Santos.
After being schooled by Alphonso Davies in an infamous 8-2 defeat to Bayern Munich in 2020, it looked as though Semedo's time was up. Barcelona were still able to turn a profit, though, with Wolves forking out £27m plus add-ons just weeks later.
Paulinho
Paulinho's move to Barcelona was greeted with some surprise in England. The Brazilian midfielder had flopped at Spurs, and a return to form in China was no guarantee he could deliver in Europe.
However, all things considered, he played an important role at Camp Nou. Nine goals in 34 games made the former Corinthians man their third highest scorer in La Liga as they won the title by a 14-point margin.
It was one-and-done for Paulinho, though. He returned to former club Guangzhou Evergrande after the World Cup, eventually on loan and then permanently, and is now playing in Saudi Arabia for Al-Ahli.
Ousmane Dembele
Dembele is the only one of the seven still at Barcelona, and he too could end up leaving this summer. The French international is out of contract at the end of the season, but improved form under Xavi and a good relationship with new arrival Pierre-Emerick Aubameyang have prompted talk of a new deal.
The former Borussia Dortmund man set Barcelona back an initial £97m, making him the highest-profile summer addition after Neymar's move to Paris Saint-Germain. However, injuries have prevented him from making the desired impact.
Now 24 years of age, Dembele has only just made his 100th La Liga appearance, in his fifth season. For those keeping score, that means he's missed nearly half of the games played by the club since his arrival.
Philippe Coutinho
When Barcelona's long wait for Coutinho ended in January 2018, it was meant to be the missing piece of the jigsaw. However, despite impressing in his first half-season, his spell has gone about as badly as one could have anticipated.
A number of fans and outsiders have considered Coutinho to be the club's worst ever season, given the combination of fee and output. The 2018-19 season is the only one in which he has been anything approaching a regular, and even that was overshadowed by his involvement as Barca were sensationally knocked out of the Champions League by his former club Liverpool.
The final insult, however, came in 2020 when he scored twice for Bayern in their Champions League demolition of his parent club. Coutinho's move to Villa ends a chapter which plenty will be desperate to put behind them.
Yerry Mina
Coutinho wasn't the only mid-season signing, though he was certainly the higher-profile of the two. Yerry Mina also moved to Camp Nou in January 2018, joining from Palmeiras in a deal worth just over £11m.
The Colombian was eased in after joining, playing just six times. However, after impressing for his country at the World Cup, Everton offered Barcelona a chance to double their money and they said yes.
Mina has impressed at Goodison Park when fit, but has missed plenty of games through injury. Considering some of the other 2017-18 deals, though, this was far from being Barcelona's worst bit of business.
