The Belgian international originally moved to west London in 2011 after signing for the Blues from Anderlecht in his homeland.
The powerful striker struggled to make an impact at the club, and despite impressing on loan at both West Bromwich Albion and Everton, he was allowed to leave for Goodison Park in 2014 after failing to score a single league goal with the Pensioners.
Despite being shown the door at Stamford Bridge, Lukaku has demonstrated his class with Everton, having scored 18 goals in 37 league appearances this term.
Now, according to the Telegraph, the Blues are keen on bringing the attacker back to the club and have stepped up their interest in the frontman.
However, it remains to be seen whether the Blues would meet the Toffees’ fee expectations, with the Telegraph reporting that the Merseyside heavyweights have slapped a £65 million valuation on the attacker.