Raheen House was less than a length third behind winner Etah James in the 3200-metre Sydney Cup at Randwick despite a torrid run in the straight, highlighting his credentials over the distance on a heavy surface.

The six-year-old gelding and stablemate Mustajeer came together several times in the hunt for inside runs, cruelling both of their chances of victory.

Mustajeer's jockey, Nash Rawiller, tried to gain a run inside of favourite Young Rascal early in the straight and made contact with Raheen House, which had Brenton Avdulla aboard.

Raheen House, which had been held up for a run, then shifted out and buffeted Mustajeer. Rawiller was later advised by stewards to exercise more care in similar circumstances.

Adding to Raheen House's troubles, Avdulla dropped his nearside rein with 50 metres remaining and did not regather it until after the winning post.

Raheen House showed strength to the line, while Mustajeer finished fourth lengths back in fifth after losing momentum.

After falling short of a Melbourne Cup (3200m) start last year when with William Haggas, Raheen House won the group 2 Chairman's Quality (2600m) last week before proving his wet-track, staying prowess again on Saturday under the care of Lees.

The placing was the only joy for Lees and Australian Bloodstock at Randwick.

Delectation Girl was fourth in the group 1 Coolmore Legacy Stakes (1600m) after a brilliant run from second last at the top of the straight, while Enchanted Heart was sixth and the best of Lees' five runners in the Provincial Championship final (1400m).

Bargain buy Through The Cracks won the $400,000 final for Gosford trainer Angela Davies.

The five-year-old gelding, bought for $7500 as a yearling, powered home under James McDonald to give Davies her biggest win as a trainer.

"It certainly is. What a great thrill it has been today," Davies said. "He just keeps improving the older he is getting. We had a slow start because he was immature but as he's maturing he's just getting better."

Sent out the $6 equal favourite in a field of 15, Through The Cracks had only four horses behind him approaching the home turn but he overhauled his rivals to beat the Tracey Bartley-trained Moana Jewel ($31) by 1.3 lengths.

The Kim Waugh-trained Oxford Tycoon ($12) was a nose away third.

"James said 'I'd like to be midfield' and I said 'don't go getting him out of his comfort zone'," Davies said.

"I said 'he's got the best finish ever, you've just got to leave him alone and he'll do the best thing for you at the end'.

"It got to about the 200 metres and I started yelling. It was great. What a great thrill.

"We're such a small stable. We've only got eight horses in work. It's such a thrill to just beat everybody else as a small trainer."

Through The Cracks had already earned $130,000 prize money while first prize money for Saturday's win, his sixth career victory from 13 starts, was another $216,000.

McDonald went into the race brimming with confidence after riding Through The Cracks in a recent Randwick trial and said the gelding had been perfectly trained for the big day.

He said he was rapt to be able to get the job done for the gelding's connections.

"He put in a fantastic trial the other day and I said to Angela I thought they won't beat him after that trial," McDonald said.

"He just had so much improvement in him, he was turned out in brilliant order and he was well.

"It was a good performance."

AAP reports: Glen Boss considered her his best long-shot ride in a Group One race and Etah James has proven him right, upsetting her more fancied rivals to win the Sydney Cup at Randwick.

Making her debut for co-trainers Ciaron Maher and David Eustace, the well-travelled mare has spent most of her career in Victoria with Matt Cumani before a brief stint with part-owner and New Zealand trainer Mark Upton.

Transferred for a Sydney Cup campaign, Etah James has proven the superior stayer in Saturday's stamina-testing edition of the 3200-metre race.

The victory gave Boss back-to-back Group One wins after he took out the Australian Oaks on Colette and while he feared English visitor and favourite Young Rascal, he had genuine confidence in Etah James.

"I've been riding it work and I trialled her here in a very fast trial and I said, 'this is just flying this thing'," Boss said.

"Its work on Tuesday was exceptional actually and I said to Ciaron this morning, this will be the best 30-1 shot I'll ever ride in a Group One race.

"I wasn't expecting to beat the English horse to be really honest but I was expecting to run one, two, three."

The win ended a 16-year Sydney Cup drought for Boss who last won it in 2004 aboard champion stayer Makybe Diva, who sandwiched it between the first two of her three Melbourne Cup wins.

Etah James did not give him quite the same feeling, but she was game.

"Most of them were off the bridle and chasing at the 600 and mine was still coming up underneath me and I thought, I'm going to run very well," Boss said.

"It's testing conditions.I don't think we broke 39 for the last 600, it was very slow."

Boss' assessment of the sectional time was not far wrong, Etah James ($14) running her last 600-metres in a dour 38.66 seconds to score by a long head over The Chosen One ($18) with another half-length to Raheen House ($6).

The $2.60 favourite Young Rascal did not appear to see out the distance.

Maher said Etah James' light weight and a great ride by Boss was the perfect recipe for Sydney Cup success.

"She is a genuine two-miler," Maher said.

"When they get down to those weights over trips like that, anything is possible.

"Glen is in elite form and gave her a peach of a ride, and it came down to a head margin

"She was ridden perfectly and everything panned out the right way."