Juggling continental concerns with domestic responsibilities can be a difficult task and it is rare that a team dominates in both spheres, with success in one competition usually inhibiting it in the other.
However, it can and has been done, with plenty of teams doing so in the days of the old European Cup - when it was a straight knockout tournament - as well as in the modernised Champions League era.
It seems that Rangers lead the way, amassing an incredible 115 pieces of silverware to fill their cabinets. Incidentally, their bitter rivals Celtic follow with 106 trophy lifts themselves - though that's not to suggest there's a duopoly on Scottish football or anything like that, right?
But to simplify things, here's a list of the top 8 teams from Europe's top five ranked leagues (England's Premier League, France's Ligue 1, Germany's Bundesliga, Italy's Serie A, and Spain's LaLiga) who have the League, National Cup, and the Champions League in the 21st Century, in the same season.
1. Barcelona: 2014-15 Season
The 2014–15 season was Barcelona's most successful seasons in the club's history as they clinched the Treble by winning LaLiga, Copa del Rey, and the Champions League. By doing so, the Catalans became the first European team to twice win the domestic double as well as the highest continental tournament, after winning their first treble in the 2008–09 season.
2. Bayern Munich: 2012-13 Season
The 2012/13 season was a breeze for Bayern Munich. Jupp Heynckes's side started the season with a nine-match winning streak, and ended the season claiming the Treble, winning the Bundesliga, the Champions League, and the DFB-Pokal. Bayern were the first German club to achieve the Treble and the third European Club to complete the Treble in the last five seasons and seventh ever in European Club competition.
3. Porto: 2010-11 Season
Porto captured their 25th league title with their April defeat of rivals Benfica and won the Europa League. The team also won the Taça de Portugal, completing a treble under manager Jesualdo Ferreira. They were the last team from outside of Europe's big five leagues to taste European glory.
4. Inter: 2009-10 Season
A decade ago, Diego Milito scored twice as Inter defeated Bayern Munich 2-0 in the Champions League final to achieve what no other Italian team had managed before. The Nerazzurri's night of triumph at Real Madrid's Santiago Bernabeu saw Jose Mourinho's side complete a Serie A, Coppa Italia, and Champions League treble.
5. Barcelona: 2008-09 Season
In 2008–09, Barcelona started a new era with a new manager, former player and Barcelona Atletic coach Pep Guardiola, who led the team to the first treble in Spanish football history. Barcelona played scintillating football throughout the season, winning the Supercopa de España, UEFA Super Cup, FIFA Club World Cup, Copa del Rey, La Liga, and the UEFA Champions League.
6. CSKA Moscow: 2004-2005 Season
Charging to the quarter-finals of the 2005 Champions League made everybody sit up and take notice of the Army Men. CSKA won the domestic league and cup double thanks to a Yuri Zhirkov winner in the latter game before turning over Sporting Lisbon in the UEFA Cup final, beating the Portugese club on their own Lisbon turf. As a result of winning the UEFA Cup they faced Liverpool in the 2005 UEFA Super Cup, which they lost 3–1.
7. Porto: 2002-03 Season
One of Jose Mourinho’s greatest triumphs is leading Porto to the treble in the 2002-03 season. The Portuguese outfit won the Primeira Liga, Taca de Portugal and the UEFA Cup in an outstanding campaign. The UEFA Cup final was one for the ages. The game went to extra-time, where Porto became the first team to win a trophy on the silver goal rule. Deco scored in the 115th minute and Mourinho’s side held on to lift the trophy.
8. Galatasaray: 1999-00 Season
In 2000, Galatasaray became the first Turkish club to have won a major UEFA competition. The bar was set high in 2000 by legendary manager Fatih Terim, who took Galatasaray to the unique treble of league, cup, and the UEFA Cup.