The Caulfield Cup is often used by overseas horses as a first Australian race ahead of the 3,200-meter Melbourne Cup, Australia's most prestigious race which will be held on November 6 at Flemington in Melbourne.
Cosgrave said it was an incredible performance and it would allow the stable to dream of Cup glory on the first Tuesday on November.
"I think anything its possible after today, we should have got beat," he said.
"We had a bad trip and everything went wrong for me but it was a great day."
The Caulfield Cup is a handicap race for three-year-olds and older over 2400m with Best Solution's connections taking home a huge prize of $3 million, while the 10th place getter will still get $120,000.
The betting had Kings Will Dream in favouritism just ahead of Youngstar and The Cliffsofmoher. The win by Best Solution, who carried top weight of 57.5kg, also made it back-to-back Group 1 wins for bin Suroor and jockey Cosgrave, who last week took the Caulfield Stakes in spectacular fashion aboard Benbatl.