Liverpool chiefs are reportedly worried that Jurgen Klopp will leave the club once his existing contract expires.
The 52-year-old has spent nearly four years at Anfield and has three years left to run on the contract extension signed in July 2016.
That will take Klopp up to seven years on Merseyside, matching the amount of time he spent at former clubs Mainz 05 and Borussia Dortmund before stepping down.
According to The Sun, there are concerns behind the scenes at Liverpool that the popular German coach is stalling on agreeing fresh terms as he does not intend to stay on beyond the summer of 2022.
Klopp, who guided the Reds to a sixth European Cup triumph in June, is said to have been offered an improved deal that would increase his salary from £7m to £10m a year.
Bayern Munich and Real Madrid were both tipped to make an approach for Klopp last year when they were searching for a new head coach.