Red Bull Salzburg manager Marco Rose is now the third favourite to be appointed on a permanent basis, behind Lennon (5/2) and Hoops legend Henrik Larsson (7/2).
Rose was as far out as 33/1 when the market opened but has been backed and is now priced at 5/1.
The former Mainz defender is on course for another Austrian Bundesliga title, and Salzburg are in the last 16 of the Europa League, having won Group B and beaten Celtic twice in the process.
Rose began his career with VfB Leipzig, spending five years at the club, before transferring to Hannover 96 and finally Mainz.
He hung up boots in 2010, and had a brief stint in charge of Lokomotive Leipzig - the latest incarnation of his former club VfB Leipzig - before joining Red Bull Salzburg as youth team boss.
After four years he took the top job, succeeding former Barcelona and Spain Under-21 midfielder Oscar.
Alex Neil, the former Hamilton and Norwich boss, is also in the running and is priced at 15/2 while RB Leipzig chief Ralf Rangnick is priced at 16/1.