Heat has won the title once under the watchful eyes of Lehmann.
The Renegades emerged victorious in an all-Melbourne finale, which saw them collect their first-ever BBL trophy.
He was in charge of the team for four years.
Stars will have to win their last league game now to go through to the semis.
This is McCullum's farewell game while Sandeep Lamichhane is set to play for the Stars.
This will be Brendon McCullum's last BBL and if Heat manages to win, then it will depend on the other results whether he will play one more game.
McCullum went unsold in the IPL 2019 auction earlier.
McCullum continues to defy the age with his athleticism on the field.
Renshaw remained unbeaten on 90 off 50 balls.
Lalor ended with the figures of 3/23 in three overs.