The forward was on Merseyside on Monday as he took part in his medical before joining Jurgen Klopp’s side.
The Reds have been locked in negotiations for the Senegal star for several weeks after Klopp reportedly identified him as a key man for his plans moving forward.
The Saints allegedly insisted that there was no prospect of Mane leaving unless Liverpool paid well in excess of £30 million for his signature.
And according to the Telegraph the deal could end up costing as much as £38.5 million as a result of extra clauses that have been inserted.
They report that Liverpool will initially pay £34.5million for him, and then based on Mane’s appearances, Liverpool’s success in qualifying for the Champions League and how they do in the competition, extra money will be added on.
Southampton were keen to add those on as they felt they were more attainable than individual achievements that are often a part of big transfers.
He will not prove to be the most expensive purchase for them though, with Andy Carroll topping the Saints stars' price by £500,000 should it be concluded as expected.