Sir Charles Road's last start was in the Gr.1 Metropolitan Handicap (2400m) at Randwick on October 5, showing the best form of his four-start campaign so far with a close third.
After being prominently positioned throughout the race, he looked vulnerable at the home turn. But rather than being swallowed up by the backmarkers, he fought strongly down the straight to be beaten by only half a length, taking his career earnings past the $1 million barrier.
"He ran pretty well last time and has done nicely since then," O'Sullivan said.
"Everything's been going well with him. He's just carried on doing the same thing, and we're pretty happy with him heading into Saturday's race."
Australian bookmakers rate Sir Charles Road a $13 chance in a St Leger market headed by Metropolitan winner Come Play With Me at $6.
Meanwhile, the O'Sullivan-Scott team will also saddle a feature-race runner in New Zealand today, with Tweedledee tackling the Listed Staphanos Classic (1950m) at Rotorua.
The 7-year-old is backing up from a gallant fourth in his home-town Matamata Cup (1600m) last weekend.
- NZ Racing Desk