Fortress Command struggled on a heavy track at Randwick but it was a different story at Rosehill where he ploughed through the conditions to post his fourth career win.

A wet track at Randwick is regarded as significantly more testing than the same conditions at Rosehill and Fortress Command underlined that theory with his win on Saturday.

Trainer Gerald Ryan initially planned to target an 1800m race on the same program before opting to keep Fortress Command to the 1500m of the Quincy Seltzer Handicap because he didn't believe his lead up run conditioned him enough.

"The idea was to run in the 1800 metre race here today but I just didn't think his run second up at Randwick was strong enough," Ryan said.

"The only place he has handled a wet track was here at Rosehill as a two-year-old."

In a race that lacked speed on paper, jockey Tommy Berry took up a forward position on Fortress Command and the four-year-old dug deep to score by a half-head over Liveinthefastlane with Petronius another length away.

Ryan said Fortress Command would back up in an 1800m race at the stand alone feature meeting at Newcastle next weekend provided he came through the win well.

All races at Rosehill on Saturday were put back by one due to a TAB system outage which prevented punters from placing bets for an extended period.

The issue, which began around 11am (AEDT) on Saturday, affected all race meetings across the country and led to South Australian racing officials postponing the final seven races at Morphettville Parks to Monday.