David Payne has been waiting for the day the penny drops with War Baron and is hoping his patience will finally be rewarded at Randwick.

The colt has a modest record with just one minor placing in seven starts but Payne has seen enough signs of his raw ability to persevere.

The youngster was warming into the race in the Fernhill Handicap in April when he clipped heels and fell inside the final 200 metres.

Second-up off a break last start at Canterbury he was forced to go back to last from a wide gate and hung out rounding the home turn before closing resolutely for fifth to Exceed The Stars.

Payne admits much of the colt's bad luck has been self-inflicted but from a good draw in Saturday's Australian Turf Club Handicap (1400m), the trainer will not be surprised to see War Baron give the race a shake.

"He's been unlucky but he's also been his own worst enemy because he still runs like a first-timer," Payne said.

"Some horses take a while to switch on. They're like kids at school. It's just a mental thing.

"All he's got to do is be a bit handier and I think he can trouble them. He's just got to put it together."

The horse who finished second to Exceed The Stars, Mandela, will again be among War Baron's opponents.

The Peter and Paul Snowden-trained youngster loomed up to win at Canterbury but threw away victory when he ducked out.

He has won a barrier trial since and is an odds-on favourite for Saturday's race with War Baron a $21 chance.

Payne does not think there is that much between them.

"The other day, I know Mandela was unlucky but so was he," Payne said.

Payne will also be represented at Randwick by Costello, who strung together back-to-back wins in February before finishing midfield in the Rosehill Guineas and ATC Australian Derby.

The three-year-old was beaten less than three lengths when he resumed behind Attention Run earlier this month and will be out to maintain his perfect second-up record in the Everest Carnival Handicap (1800m).