It's history in Spain, but it's been done before elsewhere. Goal.com's Peter Staunton profiles some of the historic treble-winning sides in the history of the European game...
No side before this incarnation of the Blaugrana has ever won La Liga, Copa del Rey and the top European prize, but four teams from elsewhere have managed the feat; all from Northern Europe.
Two British sides and two Dutch sides have completed the landmark victories, and in some cases, have even done more than that.
Euorpean Cup, Scottish League, Scottish Cup (Scottish League Cup, Glasgow Cup)
The Lisbon Lions
The entire Celtic team of 1967, coached by the legendary Jock Stein, was born within a 30-mile radius of their Parkhead stadium. The Hoops completed a quintuple of sorts that year. The team, led by captain Billy McNeill, won before and behind them.
The giants were victorious in the European Cup, Scottish League, Scottish Cup, Scottish League Cup and threw the Glasgow Cup in for good measure; winning every tournament they entered in a most unique season.
Success in Europe was a landmark occasion as Celtic became the first British team to ever lift the prestigious cup. In Lisbon, Stein's side tangled with Internazionale, master exponents of Catanaccio, for which Celtic provided a tonic.
Despite falling one behind early on, Celtic registered close to 40 attempts on the Inter goal, before finally claiming a 2-1 win. The strikes were provided by Tommy Gemmell and Stevie Chalmers. The forward's strike came just seven minutes before the final whistle.
European Cup, Eredivisie, KNVB Cup (Intercontinental Cup)
Much of Ajax's groundwork for their treble had been laid by legendary coach, Rinus Michels. The pioneer of Total Football departed the club in 1971 to take over at Barcelona after leading the Amsterdam outfit to the brink of a triplet.
He claimed all but the Dutch league in 1971, and his successor Stefan Kovacs went one better a year later.
After finishing runners-up to Feyenoord in 71, Ajax claimed the league title ahead of their perennial rivals, defeated Den Haag in the KNVB Cup and ousted Inter in the final of Europe's elite competition in the city of Rotterdam.
Johan Cruyff fired a brace as ten Dutchmen and a Belgian captured the second of three consecutive European Cups for the team from De Meer. Later, Ajax made an historic year even more memorable by defeating Independiente on aggregate to win the Intercontinental Cup.
PSV Eindhoven 1988
European Cup, Eredivisie, KNVB Cup
If you thought Jose Mourinho's Porto side were pragmatic, they were nothing compared to Guus Hiddink's PSV side that won the European Cup in 1988.
Not only did the Dutch team win the trophy on penalty kicks after a scoreless draw in the final, but they actually failed to win any of their last five matches in the competition, winning out on away goals in the quarter and semi-finals. Indeed, PSV won only three of their nine matches in the tournament proper.
Bordeaux and then Real Madrid fell by the wayside as PSV went on to face Benfica in the final. Led by Ronald Koeman and guarded by the goalkeeping talents of Hans van Breukelen, PSV held their nerve and dispatched all five of their kicks in Stuttgart after a subdued evening.
That pair were also among the Dutch international side who went on to win the European Championships that year, also held in Germany.
Domestically, PSV took out Roda in the final of the KNVB Cup; their first of three consecutive wins in the tournament. The Eredivise was also one of a hat-trick of league wins for Guus Hiddink, a feat he repeated in the years 2003-2006.
Manchester United 1999
Champions League, Premier League, FA Cup
Leaving It Late
Sir Alex Ferguson's record-breaking season has long since passed into lore, and has provided some Manchester United fans with their richest memories of the team. Late goals characterised the Treble in 1999; both Champions League semi-finals against Juventus had been dramatic, and no goal came later than Ole Gunnar Solskjaer's last-gasp winner in Barcelona against Bayern Munich in the final.
United had been behind for almost 85 minutes before Teddy Sheringham equalised on the stroke of 90 minutes. Moments later and another David Beckham corner had yielded the Norwegian's close ranger winner. Two injury time goals in three minutes of stoppage time had given Sir Alex his first Champions League.
To that he added the FA Cup, with a routine win over Newcastle United in the final. The real story of that triumph came in the semi-final against Arsenal at Wembley. The game will be remembered for Ryan Giggs' amazing slaloming run and shot in extra time after Arsenal had missed a penalty. It capped a 2-1 win and sent United to Barcelona on a high. Also in that run, there was a remarkable comeback against Liverpool at Anfield in the fourth round.
The hosts had led for over 80 minutes before United mounted a comeback.The league title was also claimed at the expense of Arsenal by a margin of only one point. A final day, 2-1 win over Tottenham Hotspur sealed it for United.
Peter Staunton, Goal.com