Barcelona was humiliated in an 8-2 loss to Bayern as they crashed out of the Champions League at the quarter-final stage.
Setien was hired as Ernesto Valverde’s replacement in January.
He failed to lead his side to a trophy in 2019-20.
Spanish football expert Balague says former Tottenham manager Mauricio Pochettino has “been approached”, but ex-Barca player Koeman would be a more popular choice.
“The board will meet tomorrow and Setien will be sacked,” Balague told the BBC 5 Live Euro Leagues podcast. “They have to choose a manager because in two weeks time pre-season starts – and the talk is Koeman could be the man.
“He said no to an offer in January, but this is different. I think his health situation may have played a part. Discussions may be taking place, we may hear tomorrow, but he will need to separate from the national side so there is still a wait for that to happen.
“He is a name who will, more or less, make everybody happy.”
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