United striker Wayne Rooney will be the subject of a third bid from Chelsea after the bank holiday encounter at Old Trafford, when Belgium forward Lukaku aims to build on his 17 goals on loan for West Brom last term.
Lukaku began the season as a substitute, replacing Fernando Torres against Hull and Demba Ba against Aston Villa, and plans to take his opportunity when it is given.
"I'm getting closer to where I need to be and hopefully also closer to the starting line-up, my main ambition," the 20-year-old former Anderlecht striker told Chelsea TV.
"If I keep working hard, like I'm doing now, showing the talent that I have hopefully I get to start in the next game.
"Compared to the first year, when I arrived here it was all about learning and taking a bit off all the players, now it's about starting games."
The physically imposing Lukaku offers a different attacking threat for Chelsea than the playmaking trio deployed directly behind the lone striker - any three from Eden Hazard, Juan Mata, Oscar, Victor Moses, Kevin de Bruyne and Andre Schurrle.
Lukaku can hold the ball up, link the play, and occupy the attentions of a number of defenders, rather than drop deep to add to the playmaking congestion.
"When you have three players like that behind you, if you come towards the ball it makes one player too much," Lukaku said.
"You need that one guy to go in there, that's a good thing, that's what I like.
"When they go to the ball I'm around to block a defender, flick the balls on or run on at the back of defence."
Lukaku is often likened to former Chelsea striker Didier Drogba, who he used to sit next to in the dressing room on his arrival from Belgium.
Mourinho has been wary of the Drogba comparison and Lukaku is too.
"There will always be comparisons but I have my own name," Lukaku said.
"I am still young and I can still make my own way."
Chelsea play United, Everton, Fulham and Tottenham in their next four Premier League matches and Bayern Munich in the UEFA Super Cup in Prague next Friday, the match which resulted in the Villa match being brought forward.
A second successive victory gave the Blues a head start in the title race, but Lukaku played down the significance of the embryonic table.
"We have six (points) out of six and we want to stay at the top of as long as possible, but we have to keep working hard," he said.
"We have a few difficult games coming up but we are ready and if we prepare well, hopefully we can do the job.
"The year Manchester City won the title two years ago, Manchester United were many points ahead and City came back.
"Anything can happen in the Premier League and it is still early at the start of the season."
Chelsea goalkeeper Petr Cech, who made some crucial saves against Villa, knows the trip to Old Trafford offers an opportunity to strike an early blow in the title race.
Cech told chelseafc.com: "We've won games at Manchester United and we've lost games there. It's always tight.
"It's still at an early stage of the season but any advantage you can gain over your rival is always good."