The pacer is set for a showdown with fellow heat winner Machie Mach in the annual Southern battle of claiming warhorses.
Four Starzzz Shiraz comfortably won the first heat of the series before putting in below-par runs in the next two heats.
In the first of those runs, the horse threw his head in the air and paced roughly down the home straight.
"We don't really know what happened that night. He just pulled that out of his hat. I am not sure what he was up to," Mowbray said.
In the latter start the horse had even more tricks when he wobbled towards the outside of the track at the 500m and then tired in the straight.
Four Starzzz Shiraz missed the last heat of the series last week in Mowbray's hope of refreshing the gelding and getting him back to his best.
Going by his recent work, the plan had worked, Mowbray said.
"I think he back to where ... he was on the nights that he was winning. We are happy enough with him going in to the race."
There are no doubts about Four Starzzz Shiraz's main rival, Machie Mach.
The horse has been brave in two runs for second after a crushing heat win three weeks ago.
Machie Mach and driver Rory McIlwrick have the advantage of barrier 4, which could make it hard for Four Starzzz Shiraz and Charlotte Purvis to catch them.
Four Starzzz Shiraz has shown a liking for leading in his races, and if he does it again it should set up an intriguing battle between the two drivers.
"Obviously it is depends on what Rory does. We obviously see him as the one to beat," Mowbray said.
Roxburgh trainer Geoff Knight said there would no be plans to change tactics for Machie Mach tonight.
"We will be driving him in a similar way.
"He is up on his toes and he is bouncing. He is ready to roll."
Rah De Rah and Westar Sam look decent place chances behind Four Starzzz Shiraz and Machie Mach.
Unlike tonight's claimers' series final, the Forbury Park junior drivers' series has already been decided.
John Morrison has a unassailable lead going in to race 6, the final heat of the series.
Woodend Beach trainer Regan Todd has a strong hand in the race with Omar Sharif and Possente Cavallo who will start from barriers 1 and 4 respectively.
Todd favours the consistent Possente Cavallo over his talented but unreliable stablemate.
"Possente Cavallo went really well at Forbury last time, so she should be a good chance," he said.
"Omar Sharif has got the motor there, but he is inconsistent. It just depends what horse shows up on the night."
Canterbury junior driver Andrew Fitzgerald pulled off a rare feat before tonight's meeting.
He secured the services of Dexter Dunn to drive Black Art, the pacer he trains, in race 8, tonight's feature pace.
Dunn and trainer Graeme Anderson are usually an unbreakable combination at Forbury Park meetings. They combined to win with Command Lustre at the track last week.
Jonny Cox will substitute for Dunn on the horse, who will clash with Black Art.
Fitzgerald will drive outsider Neve Franco in tonight's junior drivers' race.
