Pep Guardiola has challenged Hansi Flick and Bayern Munich to a 'battle of the sextuples' after the Bundesliga giants matched his Barcelona team's achievement with a sixth straight trophy, Goal reported.
Bayern beat Tigres to win the Club World Cup on Thursday, adding to their Bundesliga, Champions League, DFB-Pokal, UEFA Super Cup and DFL-Supercup titles over the last year.
In doing so, they became only the second side ever to win the sextuple, matching Guardiola's legendary 2009 Barcelona team.
In a video message on Twitter, Guardiola said: "Big congratulations to all the Bayern family for this incredible success, to be the Club World Cup champions and especially to win six titles.
"We are so proud, I am so proud, a big congratulations for everyone, especially Hansi [Flick], the players and the backroom staff for this amazing thing.
"But I would like to say to Hansi that you are the second team to win the six titles in a row!
"Before you, there was another team, Barcelona… so maybe I can call Messi and company and we can play for the seventh title? Tell me when and where and we will be there!"
Bayern almost won the sextuple under Guardiola in 2013. After Jupp Heynckes had won the treble in 2012-13, Guardiola won the Club World Cup and UEFA Super Cup in his first season in Bavaria, but lost to Borussia Dortmund in the DFL-Supercup.
While Guardiola had a smirk on his face as he challenged his former club, he is still hugely popular at both Barca and Bayern so he could have the pulling power to broker an exhibition match.
Of course, the 12-year gap between the two sides would put Bayern at quite the advantage on the field.
While they have just confirmed themselves as champions of the world, only three players who started Barca's 2009 Champions League final win - Lionel Messi, Sergio Busquets and Andres Iniesta - are still playing.