Lillee, who terrorised opposing batsmen bowling in tandem with Jeff Thomson 30 years ago, has pushed Johnson's case for an Ashes debut in the opening Gabba Test next month if he continues his strong early season form.
Left-armer Johnson, who is in India with Australia's Champions Trophy squad, is expected to be given increased responsibility in the one-day tournament following the withdrawal of Stuart Clark with a thigh strain.
Lillee, who hailed Johnson as a once-in-a-lifetime prospect after spotting him as a youngster in north Queensland seven years ago, has been monitoring his form from a distance.
"If he bowls well early in the season he has to be in contention (for the Ashes)," Lillee told the Sunday Telegraph.
"He's looked all right since he was 16 years of age.
"He has had a few problems along the way with injuries. Last year he told me he had had a change of attitude and that he was now leaving no stone unturned.
"He said he felt much better for it and was bowling better for it. It seems like everything is falling into place for him now."
Johnson, who took 4-11 against India in a one-day game in Malaysia last month, told the newspaper: "(A Test spot) is in the back of my mind, but I try and not think about it too much.
"I'm just concentrating on the Champions Trophy and seeing what happens there.
"I still do pinch myself a little bit. I've got guys like Brett Lee telling me how eager he is to go out and bowl with me. It's just a great feeling to play for Australia."