José Mourinho has been impressed by Romelu Lukaku over the early weeks of his second stint in charge of Chelsea and has suggested he would be happy to start the young Belgium striker in the first team when the Premier League campaign begins next month.

Lukaku, who spent last season on loan at West Bromwich Albion, scoring 17 goals, followed up his match-winning penalty in last week's victory over Singha All Stars in Bangkok with another reward and assist in the 4-1 win over a Malaysian XI on Sunday. The 19-year-old had initially envisaged spending the forthcoming campaign gaining experience via regular football elsewhere in the division but Mourinho has since made it clear he wishes to retain the forward in spite of his on-going pursuit of Manchester United's Wayne Rooney.

The teenager has started each of the pre-season games to date – Demba Ba will begin against an Indonesian XI in Jakarta on Thursday – with Mourinho encouraged by his desire to learn. "Lukaku had a fantastic manager last season but Steve [Clarke] is Steve, I am me and West Brom is not Chelsea," said the Portuguese. "It's up to the kid but he's open and intelligent to learn the kind of movement we want.

"The role he played tonight was the right movement. We don't want the striker just aiming between the central defenders but making movements, sometimes between the midfield or moving wide. People compare him to Didier Drogba but we have to respect Didier, because he is unique in Chelsea's history, and we have to respect Lukaku. The best way to do that is not compare him to a legend in Chelsea's history. Leave Didier where he is, at the top of Chelsea's history, and leave Lukaku to work hard. The kid is good."

Chelsea's interest in Rooney is maintained and an improved offer is to be lodged at around £25m, though there is an acceptance they may have to be patient to secure the player, particularly with Chelsea due to play at United on 26 August. Asked if Lukaku could challenge Fernando Torres for a starting place, regardless of the Rooney situation, Mourinho merely added: "Of course."

Another Belgian hoping to be in contention against Hull on 18 August is the midfielder Kevin de Bruyne, who hurt his right knee while volleying Chelsea's second goal against the Malaysians.

The £8m signing from Genk left the field on a stretcher with the club doctor in close attendance but he was able to hobble back to the dug-out in the second half. He will be assessed again on Monday – the team travel to Jakarta 24 hours later – but will remain with the touring party and expects to return to training later in the week.

"When he was on the floor and asking for a change, everyone on the bench thought the worst," said Mourinho. "The first assessment by the doctor is that it's not ligaments, that's for sure, and if it's something in the meniscus it has to be a very small injury. So we believe it's not an important injury. Hopefully it isn't because the kid is a fantastic player and showing match after match, and in training, that he's going to be a key man on the pitch."

Chelsea's other goals were scored by Victor Moses and Bertrand Traoré, the latter a 17-year-old triallist who will sign a professional deal at the club when he turns 18. Chelsea have been unable to secure the eight-time Burkina Faso international on a professional deal up to now because he holds only a student visa, despite spending a similar six-week period on trial at Cobham last season. He will most likely then be loaned out to a club in Europe with Chelsea unlikely to be granted a work permit to continue his footballing education in England.

"Those are the rules in England and we have to accept them," Mourinho said. "They have justification. Now we want to keep him. We'll have to wait until he becomes 18 to try to get the permit for him to stay in England. If it's not possible we have to let him go on loan somewhere but we have the guarantee that he plays for his national team.

"For a 17-year-old boy, sooner or later, the committee has to give him a permit to play in England. If he goes on loan somewhere, he has to go but, if he's playing for his country at the same time – one of the most important countries in African football – he'll get his deserved permit. So no dramas with it. It's fantastic for him to come here and play well for Chelsea."