Emerging stayer Astronomos has shortened in markets for the Group One Metropolitan with a return to winning form at Randwick.

The gelding made amends for his last-start seventh at Rosehill and lived up to the expectations of punters who sent him out the $3.70 favourite when he came from last to overhaul Loophole ($5.50) in Saturday's Benchmark 83 over 2000 metres.

His trainer David Vandyke admitted Astronomos' habit of missing the start was a concern but his finishing sprint more than made up for it.

"He pulled up well after Rosehill but it's hard to get a line on him in trackwork," Vandyke said.

"He's not a good worker. In fact he's at the bottom of the list.

"But he knows what is expected of him now and knows where the finish line is."

Vandyke said the Newcastle Gold Cup (2350m) on September 18 would be the next port of call for Astronomos whose record now stands at six wins from nine starts.

"I think the 2350 metres at Newcastle will be ideal for him," Vandyke said.

"He's ready to take that step now.

"This is the most relaxed he's been before a race."

The TAB tightened Astronomos from $26 to $15 for the Group One Metropolitan (2400m) on October 3.