Lukaku drilled a first-half penalty to give new-look Chelsea a 1-0 win over the Singha All-Star XI, who humbled Manchester United by the same scoreline last week.
Lukaku, who starred on loan with West Bromwich Albion last season, has vowed to fight for his place even if Chelsea sign a striker of the calibre of Manchester United’s unsettled forward Rooney.
And his goal, on a night of promising debut performances by Chelsea’s new signings in Bangkok, comes after the club ended widespread speculation by confirming a bid for the England forward.
Chelsea played with their shirt names and numbers in Thai but home goalkeeper Narit Taweekul nearly went further with the generosity when he palmed a loose ball against the crossbar.
Kevin De Bruyne was a chief threat on his debut, after returning from a loan spell at Werder Bremen, and he whistled a thunderous shot past the upright on 23 minutes.
Lukaku was also posing problems early on and he forced a sharp save from Narit after galloping through one-on-one on the half-hour.
The first goal of Mourinho’s new era came from the spot after right-back Wallace, the new signing from Fluminense, went down under a challenge in the box.
And Lukaku made no mistake with his left foot as he drove the penalty low and to the ‘keeper’s right for his first goal in a Chelsea shirt, with 35 minutes gone.
The Belgian might have had another but Narit was again equal to his first-time shot in the box six minutes before half-time.
Both teams switched nearly their entire teams at half-time — with Mourinho retaining only De Bruyne — and it was a disjointed second period from the Blues.
Eden Hazard’s free kick drew a strong save from incoming ‘keeper Thanongsak Panpipat, and Branislav Ivanovic nearly bundled another set-piece over the line at full stretch.
Hazard was nearly on target again shortly afterwards but his shot became tangled in the legs of 18-year-old debutant Nathaniel Chalobah.
Chelsea now head to Kuala Lumpur and then Jakarta as they continue their build-up to the new season under Mourinho.
The ‘Happy One’ won two Premier League titles, two League Cups and the FA Cup during his first stint at Chelsea, before successful stints at Inter Milan and Real Madrid.
United are reported to have rejected Chelsea’s bid for Rooney, despite new manager David Moyes describing him as a back-up for Dutch marksman Robin van Persie.