Portsmouth chairman Milan Mandaric has threatened to sack manager Alain Perrin unless there is an immediate improvement in results.
Mandaric is concerned by Portsmouth's form, with the club 15th in the Barclays Premiership and just two points clear of the relegation zone.
A trip to Anfield to face a resurgent Liverpool tomorrow is followed by the visit of champions Chelsea to Fratton Park and away games at Manchester United and Tottenham.
Mandaric insists he will not give Perrin an ultimatum, but expects Portsmouth to win at least one of those next four league fixtures.
"I am concerned. At the end of the day I am responsible for results so I have got to do what I have got to do," Mandaric warned.
"I am not going to give ultimatums of one, two or 10 matches. You have got to back your manager 100 per cent whether it is for one game or 10 seasons.
"But of course I am not very happy with our results and our position. If that means I have to change the manager one day, we have to face facts soon. I have done it before.
"We are going to have to pick up some points from our next four games. I expect us to win at least one of them.
"We are going to take one game at a time and see where we are going. I am going to monitor our situation closely," the Pompey chairman added.
