Fillies have been to the fore in the major two-year-old races so far this season and they hold the key to the Group One Sires' Produce Stakes.

Both Group One races for juveniles this season have been won by fillies, with Catchy taking out the Blue Diamond in Melbourne while She Will Reign led home a female trifecta in the Golden Slipper at Rosehill earlier this month.

While She Will Reign will not be in action in Saturday's Sires' Produce Stakes at Randwick, the minor placegetters from the Slipper, Frolic and Tulip, head the betting for the 1400m race at $4.60 and $6 respectively.

Trainer Mark Newnham acknowledges the dominance of the fillies so far this season but will be hoping the rise to 1400m in the Sires' brings lightly raced colt Diamond Tathagata into contention.

Newnham, a former jockey and then right-hand man to champion trainer Gai Waterhouse, began training in his own right last year and Diamond Tathagata earned his chance in the $3.5 million Golden Slipper with a first-up win this preparation in the Skyline Stakes.

The colt then finished seventh in the Golden Slipper on a heavy Rosehill track after being hampered twice during the race.

Newnham said the Sires' Produce and Champagne had been targets for the colt who is at $15.

"He pulled up well from the Slipper," Newnham said.

"He met a bit of interference and might have finished a couple of lengths closer but the fillies have been better all year and they were better again.

"The start of this preparation was pretty much aimed to get to the Sires' and the Champagne.

"He had only had one run prior to the Slipper, but you don't pass up a chance to run, especially with a colt.

"So he'll be well suited to 1400 and 1600 metres."

Newnham has also accepted for Righteous Mate in Saturday's Group One $2 million Australian Derby (2400m).

Righteous Mate is an outsider in blue riband and while Diamond Tathagata's form is on wet tracks, Newnham wants it to dry out for his Derby contender.