Financially-troubled Portsmouth will reportedly earn around £1m if Liverpool remain top of the Premier League table for the remainder of the season.
Sky Sports News understands that the south coast club would collect a healthy fee due to a clause written into Glen Johnson's contract when he moved from Fratton Park to Anfield in 2009.
Neither club would comment on this story but a source has confirmed the existence of the clause.
Portsmouth, FA Cup winners in 2008 and beaten finalists two years later, have since dropped down three divisions and are currently fourth from bottom in League Two - and another relegation would see them slip into the Football Conference.
Liverpool are two points clear at the top of the Premier League table.