Reds boss Brendan Rodgers is thought to be ready to delve into the transfer market in January in a bid to bolster his squad and maintain their fine start to the Premier League season.
A new winger is thought to be a priority for the Northern Irishman, and John is said to be on his wish list.
The 21-year-old has fallen out of favour with Benfica coach Jorge Jesus this term, prompting rumours that he may be available in the New Year.
Although Rodgers has the likes of Victor Moses, Raheem Sterling, Iago Aspas and Luis Alberto all available to him to operate on either flank, he is thought to be keen to lure John to Anfield to support Daniel Sturridge and Luis Suarez.
The one-time Holland international was signed by the Lisbon side for around £12m last year, and it’s likely that his current employers will be looking to recoup that fee in January.
Eredivisie giants Ajax are also watching the situation, but the lure of English football in the build-up to the 2014 World Cup may tempt John.