The Underwood Stakes will be a week later this year in a move designed to provide a better flow of weight-for-age Group One races to the Cox Plate.

Racing Victoria announced changes to the spring program on Tuesday with the Underwood Stakes at Caulfield moving from September 19 to September 26.

Last year the Makybe Diva Stakes and Underwood were a week apart but under the new program there will be two week gaps between races as they increase in distance to the $3 million Cox Plate (2040m) on October 24.

The Memsie Stakes (1400m) is on August 29 followed by the Makybe Diva (1600m, September 12), Underwood (1800m, September 26) and Caulfield Stakes (2000m, October 10) in the lead-up to the Cox Plate.

"With the upgrade of the Memsie and Makybe Diva Stakes to Group One status in recent years, and now confirmation of the change of date for the Group One Underwood Stakes, we believe we have the ideal program of spring weight-for-age races culminating in the Cox Plate," Racing Victoria's racing operations manager Paul Bloodworth said.

The sprint program has also been altered with the Moir Stakes reduced from 1200 to 1000m and the Group Two Schillaci Stakes increased from 1000m to 1100m.

The Moir will become one of only two Group One sprints over 1000m on the Australian calendar, joining the Lightning Stakes which is run in autumn.

"The distance changes to both the Moir Stakes and Schillaci Stakes will allow sprinters aiming for the Manikato Stakes and/or the Darley Classic a gradual build-up in distance as well as providing greater variety in the Group One sprints throughout the spring racing carnival," Bloodworth said.