Promising filly Royal Tithe made light of doubts about her effectiveness on a heavy track when she earned herself a winter carnival campaign on Tuesday.

Royal Tithe was expected to start odds-on after being placed behind top Queensland two-year-olds Zelady's Night Out, Candika and Love Spy at her only three starts.

However, the skies opened over the Sunshine Coast racecourse before the first race and the track was downgraded to the heavy range before the Stanley River Plate.

Royal Tithe drifted to $2.50 before beating her stablemate Stryking Stunnah ($5) by 7-1/4 lengths.

Trainer John Zielke has a good opinion of Royal Tithe who is owned by his biggest client Evan Hartley's Dovedeen syndicate.

"She will go for a spell now and come back for the winter carnival. She is that good and will get even further in distance," Zielke said.