The quartet of players are Germany international Jonas Hector, young Leicester left-back Ben Chilwell, Raphael Guerreiro of Lorient and PSV Eindhoven’s Jetro Willems.
Alberto Moreno is currently Jurgen Klopp’s main left-sided defender, but the Spaniard has failed to convince, leading to Nathaniel Clyne being shifted away from his berth on the right to cover the position.
But, reports claim that the club are keen to solve the issue long-term, with between £5m-£10m set aside for one of Chilwell, Guerreiro, Willems or Hector.
All four have varying levels of experience, with Chilwell, 19, the least known of the players.
Hector, Willems and Guerreiro are all senior internationals for Germany, the Netherlands and Portugal respectively.