Only eight teams throughout history have managed to win everything in one season. The only ones to have done it twice were Barcelona, first in the 2008-9 season and then years later in 2014-15. 'Los Cules' are in contention to do it for a third time this campaign.
Let's take a look at the teams who still have a mathematical chance of winning a treble in Europe:
Barcelona
Champions League: Set to battle it out in their last-16 second leg after a 1-1 draw at Stamford Bridge.
League: Eight points clear of second-placed Atletico Madrid at the top of La Liga.
Cup: Must overcome Sevilla in the final on April 21 to win the Copa del Rey.
Bayern Munich
Champions League: Almost guaranteed progression to the quarter-finals after thrashing Besiktas 5-0 in the first leg.
League: 20 points ahead of the chasing pack in the Bundesliga.
Cup: Set to play the semi-final against Bayer Leverkusen on April 17.
Besiktas
Champions League: Face an uphill battle to qualify for the next round after suffering a 5-0 defeat to Bayern in the first fixture.
League: Currently in second place, but have the same points as Galatasaray in first.
Cup: Must overcome Fenerbahce in the semi-final.
Juventus
Champions League: Already through to the quarter-finals after dismantling Tottenham in their Round of 16 tie.
League: Stuck in a battle with Napoli for the crown but are currently one point clear of their rivals with a game in hand.
Cup: Into the final where they will take on AC Milan on May 9.
Manchester City
Champions League: Through to the quarter-finals after beating FC Basel 5-2 on aggregate.
League: 13 points ahead of Manchester United in second.
EFL Cup: Already won the trophy after thrashing Arsenal 3-0 in the final in February.
Shakhtar Donetsk
Champions League: Have a slim 2-1 advantage over Roma with the second leg to be played at home on Tuesday.
League: Six points clear of second-placed Dynamo Kiev.
Cup: Set to battle it out with Illychivets in the semi-final on April 18.
Chelsea:
Champions League: Head to the Camp Nou in the last-16 after drawing 1-1 at Stamford Bridge.
League: Currently sat in fifth, 22 points behind Manchester City.
FA Cup: Set to face Leicester in the quarter-finals on March 18.
Manchester United:
Champions League: Set to Welcome Sevilla to Manchester for the second leg of their last-16 game with the tie currently goalless.
League: Currently second, trailing leaders Manchester City by 13 points.
FA Cup: Face Brighton in the quarter-finals on March 17.
Sevilla:
Champions League: Head to Old Trafford for the second leg of their last-16 clash with the tie finely poised at 0-0.
League: Fifth, 27 points behind leaders Barcelona.
Cup: Face Barcelona in the Final of the Copa del Rey on April 21.