The Egypt international has been a revelation since joining the Kops in the summer, scoring with ease.
On Saturday, his matchwinner against Crystal Palace took his tally for the season to 37 goals in all competitions.
However, in Wednesday's Champions League quarter-final tie, they face English Premier League champions-elect, City and Souness believes that the summer signing's only chance to beat his closest contender, Kevin De Bruyne and others to the individual accolade is by ousting Pep Guardiola's side.
"Scoring goals is the hardest thing in football and Salah has done that better than anyone else this year," Souness told Omnisport.
"If [City] beat Liverpool though, then people will be talking about City players and not Liverpool players because that will be the season over.
"If City end up winning the Premier League and the Champions League, you'd be picking someone from that team.
"Salah's had a great year and if he doesn't win it, he must be runner-up."