The unbeaten 2000 Guineas and Derby hero heads a field of 11 with Main Sequence the 7/1 2nd favourite.
Imperial Monarch, second of the three remaining O’Brien inmates, is available at 8/1 with William Hill.
Guarantee has been a notable mover in recent weeks, with his odds now 12/1 from the 20/1 quote following his York win.
William Hill spokeswoman Lucy Rhodes said “Anything that John Gosden sends for an attack on the St Leger must be afforded great respect, while Guarantee has been creeping towards the head of the market recently. However they may all be playing for places behind the juggernaut that is Camelot”
Ladbrokes St Leger: 2-5 Camelot, 7-1 Main Sequence, 8-1 Imperial Monarch, 9-1 Michelangelo, 10-1 Thought Worthy, 12-1 Guarantee, 20-1 Encke, Thomas Chippendale, Ursa Major, 66-1 Chamonix, 200-1 Dartford (EW 1/5 1,2,3)
Ladbrokes St Leger – William Hill betting w/o Camelot market: 11-4 Main Sequence, 7-2 Imperial Monarch, Michelangelo, 4-1 Thought Worthy, 9-2 Guarantee, 9-1 Encke, Thomas Chippendale, Ursa Major, 33-1 Chamonix, 100-1 Dartford (EW 1/5 1,2,3)