The pursuit of Manchester United striker Wayne Rooney has placed Chelsea's forwards under increased scrutiny and 20-year-old Lukaku has thrived so far in pre-season.
After 17 goals on loan at West Brom last term, Belgium striker Lukaku top-scored on Chelsea's tour of Asia with four goals, including a double in the 8-1 defeat of the BNI Indonesia All-Stars.
Cahill said: "He had a great loan spell at West Brom last season, has been flying in training and scored two great goals (in Jakarta).
"I don't see why he shouldn't be a Chelsea player. I play against him in training a lot and he's a handful just with his pace and power.
"His finishing is great too. He's still a young lad, but scored a lot of goals at West Brom last season.
"It's exciting times for him and I'm sure he's looking forward to the season."
Another player who impressed in Asia was 17-year-old Burkina Faso international Bertrand Traore, who, due to regulations, is not yet a Chelsea player.
Traore scored in Malaysia and a spectacular goal in Indonesia also announced his ability, with Chelsea poised to sign him as soon as he reaches his 18th birthday.
"It's too early to say he's ready to do this and that, and we don't want to get carried away, but he's certainly not looked out of place in training alongside some top international players," Cahill said.
Source: PA
Source: PA