Booming, C'est La Guerre, Innocent Lady, King's Rose, My Scotsgrey, Roi D'Jeu, Tinseltown and Auckland Cup winner Titch have also been entered.
Queen Elizabeth may have a runner as Tactician is one of two stayers entered by English trainer Michael Bell.
Tactician emerged as a contender when he won the listed Silver Cup (2800m) at York on July 9.
Racing Victoria's international recruiter, Leigh Jordon, said O'Brien was a big chance to return with one of the runners, but his Ballydoyle Stables first had to be cleared for quarantine by officials.
"I've been speaking to Aidan and he has definitely shown a keenness to return to Melbourne," Jordon told the Herald Sun.
"I would say there's a big chance one of his runners will come out if the quarantine situation can be sorted out."
Jordon said he was confident the issue would be sorted out in the next fortnight.
"We have a good working relationship with the Government and we are sorting through a couple of issues, mainly involving the location of the stables. There was a similar problem at Newmarket, which was sorted out recently," he said.
Moonee Valley chief executive Michael Browell said the club had got to first base by having So You Think as an entry and he would continue to liaise with O'Brien to get him to run.
Jordon said it was a strong international entry with group one horses from England, Ireland, France and Japan, and also 2010 US Breeders Cup Turf winner Dangerous Midge, top Japanese stayer King Top Gun, Hong Kong's Mighty High and last year's Melbourne Cup winner, Americain.
Godolphin did not have an entry in the Caulfield Cup or Cox Plate, but an RVL spokesperson said it has indicated it would be in town for the Melbourne Cup.
Victorian owner Lloyd Williams confirmed at least four of his staggering 23 stayers entered for the Caulfield Cup would return to racing in Saturday's A$150,000 Aurie's Star Handicap (1200m) at Flemington. "We'll be running Midas Touch, At First Sight, Alandi, Green Moon and possibly London Stripe as well," he said. Alandi has also been nominated for the NZBI Classic at Hastings on October 1.
Americain's bid for back-to-back Cups has been reignited after he won the Prix De Reux Stakes (2510m) at Deauville on Tuesday.
The victory pleased his trainer Alain de Royer-Dupre as Americain had failed in two starts in April but after the win he believes he is back to his best.
De Royer-Dupre told the Racing Post that Americain was a seasonal horse who found his form at the same time each year.
"The horse is now spot on," de Royer-Dupre said.
"He was not happy in the spring, and it takes time to recover after crossing the world."
American sat off the speed and swooped home in the final 200m to win by a length.
The trainer said he would have one more start in France in the Prix Kergolay, which he won last year, before heading to Melbourne.
He suggested he might not have a run in Melbourne before the Cup.
De Royer Dupre had also nominated Americain for the Caulfield Cup and the Cox Plate.
-AAP
