Peters Investments and co-trainers Grant and Alana Williams have suffered a blow ahead of the Ascot carnival.
Classy mares Spritely Star and Magical Dream have been both ruled out with injury and illness respectively.
Spritely Star, a daughter of Statue Of Liberty, won three races and was placed twice from six starts.
The four-year-old bows out of racing with consecutive wins at Northam and Ascot.
“Her racing career is over, she won’t race again,” Bob Peters told The Races WA.
“She injured her knee out of her last win at Ascot.”
Magical Dream’s future is less clear, according to Peters.
The Dream Ahead four-year-old has finished top three in eight of nine races.
Her signature victory came last year when she took out the Listed Belgravia Stakes (1200m).
She also ran third in the Burgess Queen Stakes (1400m) and second to Kissonallforcheeks in the Breeders Classic (1400m).
Magical Dream defeated stablemate Secret Plan and Hot Zed in a 1200m handicap at Ascot last Saturday.
“I’m not sure with her at the moment,” Peters said.
“I’ve sent her to hospital where she has a pretty bad case of scours.
“I’m not certain where she is at or what the future holds.
“It’s disappointing, but we are getting pretty used to it.”
Spritely Star and Magical Dream were entered for the Group 1 Railway Stakes (1600m) on November 20.
Peters hopes for a change of fortune at Ascot this Saturday in two of the feature races.
Western Empire tackles the Group 3 Asian Beau Stakes (1400m) and holds $2.50 Tabtouch favouritism.
The four-year-old gelding is coming off hot form from his previous campaign and looked sharp in winning two warm up trials.
Western Empire won the Lex Piper Stakes (1600m), the Roberts Stakes (1800m), the Melvista Stakes (2200m) and WA Derby (2400m) in a brilliant campaign of racing between February and April earlier in the year.
Stageman, third to Elite Street in the Crawford Stakes (1000m), is rated a $6 chance to turn the tables in the Tabtouch-Prince Of Wales Stakes (1000m).
Elite Street, the reigning Winterbottom Stakes champion, has firmed into $2.70 after he opened at $2.90.
In Melbourne, Peters’ Superstorm is $11 in the Group 1 Cantala Stakes (1600m) at Flemington.
After winning the Feehan Stakes (1600m) at Moonee Valley, he followed up with thirds in the Underwood Stakes (1800m) and Toorak Handicap (1600m).