That is according to bookmaker Betway, who have Lukaku odds-on to score more goals than Rooney when Manchester United host the Toffees.
United allowed Rooney to return to Everton in July after 13 years at the club.
Jose Mourinho replaced him in attack with Lukaku, who moved in the opposite direction for an initial £75m.
Betway spokesman Alan Alger explained: “Manchester United don’t appear to have any problems up front at the moment.
“Their main man Romelu Lukaku can be backed at 4/11 to outscore Rooney in Sunday’s late kick off and is also 8/15 to work the keeper more.
“Rooney has started his second spell at Everton in good form, though.
“He’s hit the back of the net in two of his four league games and can be backed at 5/2 to outscore Lukaku on Sunday.”
Rooney, who hit 253 goals for United, is the club’s top goalscorer of all time.
He picked up 11 major honours including five Premier League titles and the 2008 Champions League during his time at Old Trafford.
Paul Pogba will miss the game after suffering a hamstring injury in the Champions League win over Basel on Tuesday.
Starsport understand he is set to miss at least a month of action.
Speaking about the blow, United defender Daley Blind said: “He will be a miss, of course.
“I don’t need to describe what kind of player he is and how important he is for the team.”
