On Friday, Los Cules were humiliated in the Champions League after suffering one of the heaviest defeats in their history as Bayern won 8-2 to progress to the semi final of the competition.
It was a result which summed up the decline of Barcelona, as the 2019/20 campaign represents the first season in 12 years in which they have failed to win any silverware.
Following the loss, they quickly dismissed head coach Quique Setien, with speculation rife as to who his replacement might be.
Koeman was mentioned immediately, and was confirmed as the new boss by the Blaugrana on Wednesday.
Perhaps a bigger issue coming out of the Bayern defeat was the future of Messi, with the Argentine reportedly ready to leave the club he has been with since his early teens, disenchanted with results on the pitch and the way the club is run at boardroom level.
"Messi wants to finish his career at Barca, he has said it many times,’ Bartomeu said.
"I have spoken with Koeman and he has told me that Messi is the pillar of his project.
"Messi has a contract at Barca until 2021, he knows it and we all know it. I speak regularly with Messi and especially with his father.
"There is a project, that a new coach will arrive and he is counting on him. Messi is still the best player in the world…and each project that is done is done thinking that we have the best player in the world and in making his qualities grow."