Barcelona have sacked coach Quique Setien following the club's humiliating 8-2 Champions League defeat to Bayern Munich, the club announced on Monday, with sources confirming to ESPN that Ronald Koeman is in advanced talks to take over.

The decision to dismiss Setien was announced after a board meeting, but sources told ESPN it had already been made prior to the Bayern game.

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"The board of directors has decided that Quique Setién will no longer be coach of the first team. This is the first in a series of decisions that outline an ample restructuring of the first team. Those changes will be made in consensus with the current technical secretary and will be announced in the upcoming days," Barca said in a statement.

ESPN reported on Friday that Barca had already begun sounding out potential replacements. For a long time, the overriding feeling among the Barca hierarchy was that Setien, hired just seven months ago, had failed to win over the dressing room because of his relatively limited achievements as both a player and a coach. That led to shortcomings on the pitch in the end, with Barca enduring their first trophy-less season since 2007-08.

Barca want their next appointment to be a name that garners immediate respect among the players. Mauricio Pochettino and Xavi Hernandez were among the initial candidates, but negotiations with Koeman are progressing well and the Netherlands coach could be announced in the coming days.

Koeman, who was part of Johan Cruyff's "Dream Team" as a player at Barca and later acted as Louis van Gaal's assistant at Camp Nou, would have to leave his role with the Dutch national team for a role he's always described as his dream job.

Setien's dismissal is unlikely to be the only consequence of the thrashing against Bayern, which was the club's record defeat in a European game.

Speaking after the game, defender Gerard Pique, offering to leave himself, said changes were needed at all levels of the club. President Josep Maria Bartomeu assured that big decisions would be taken. Bartomeu is under pressure to resign but has instead decided to bring forward presidential elections, scheduled for next summer, to March.

Meanwhile, reports suggest Lionel Messi has told the club he wants to leave. Sources at the club have told ESPN they have received no communication to that effect from the player.

Setien, though, becomes the first casualty of the Bayern loss. The former Real Betis boss' fate had already been sealed after missing out on the La Liga to Real Madrid, while his relationship with the players had unravelled during the final weeks of the season as the title slipped away.

Sources told ESPN after the 2-2 draw against Celta Vigo on June 27 that some members of the squad did not click with the manager or his assistant Eder Sarabia from day one. The following month, Messi's comments after defeat to Osasuna, in which he said that that Barca have been "weak" and "inconsistent" since January, were taken as a criticism of Setien.

The two held clear-the-air talks and the players and coaching staff pulled together ahead of a Champions League round-of-16 second-leg win over Napoli, but the subsequent elimination against Bayern raised further questions about Setien's future and Bartomeu opted to sack a coach for the second time this year.

Setien replaced Ernesto Valverde on Jan. 13, taking over a side that had just been knocked out of the Spanish Supercopa but that topped La Liga and was still in the Copa del Rey and Champions League.

Defeat to Athletic Bilbao, though, ended Barca's hopes of appearing in a seventh successive domestic cup final and was followed by a failure to beat Madrid in the league title race.

Barca held a two-point lead when the league resumed in June following the lockdown in Spain caused by the coronavirus pandemic, but dropped points against Celta, Atletico Madrid, Sevilla and Osasuna, allowing Madrid to go past them to claim top spot.

Setien had been brought in with the aim of restoring the essence of Barca's footballing philosophy, but sources told ESPN that several members of the club's hierarchy feel he failed to do that. The problems might run deeper than one man who had the job for such a short time, but he has ultimately been made the face of a barren season.

Setien could argue he wasn't dealt the best hand. Barca had to make the emergency signing of Martin Braithwaite from Leganes in January to make up squad numbers, and for several post-lockdown games had only 14 first-team players available.

If appointed, Koeman will become the club's third manager of the year but takes over with the added difficulty of the uncertainty surrounding the future of the club.

With presidential elections to come in March, he arrives with the understanding that he could be out of a job in less than 12 months if the incoming president -- Bartomeu cannot stand again -- wants to bring in his own man.

Meanwhile, Barcelona goalkeeper Marc-Andre ter Stegen will miss the mid-September start of the 2020-21 season in order to have surgery on a long-term knee problem.

Ter Stegen will have an operation on the patellar tendon in his right knee on Tuesday. Sources close to the player say he will be out for around two months, with the new La Liga season scheduled to begin on Sept. 12.

"I discussed this 'clean up' with medical experts as there were some irritations earlier this season," Ter Stegen wrote on social media. "It's a proactive intervention in order to prevent and prepare for the future. I will need some weeks to recover and to return to 100 percent. I'm calm and positive about the situation, I will come back soon.

Ter Stegen missed a number of games in January, including the Spanish Supercopa defeat to Atletico Madrid, as he received treatment on the injury. That enabled him to complete the campaign but the problems did not disappear and he has opted for surgery.

The 28-year-old's contract expires in 2022 and sources close to the player have always maintained his desire is to remain at Camp Nou, but needs to be convinced that Barca are heading in the right direction on the pitch.