The Dutchman retained the faith of Joan Laporta for the 2021-22 campaign in spite of Barca's disappointing La Liga and Champions League finishes, but the pressure is weighing heavier on his shoulders.
La Blaugrana had to rely on a late Ronald Araujo header to rescue a point against Granada in Monday's top-flight clash, and their Champions League campaign kicked off with a humbling 3-0 home defeat to Bayern Munich.
According to Goal, Barca are preparing to relieve Koeman of his duties during the next international break, and the Catalan giants have identified Martinez as their top target for a successor.
The report speculates that Martinez may be open to leaving his Belgium post having failed to win a major trophy during his reign, and Barca are close to formulating a £10m severance package for Koeman's exit.
Martinez has won 50 of his 64 games in charge of Belgium, but the former Everton and Wigan Athletic boss will see his deal expire next year.
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