Makeshift halfback Casey McGuire put a mortgage on the vacant Brisbane No.7 jersey with a standout performance in the Broncos' 24-22 National Rugby League win over St George Illawarra at Suncorp Stadium.

McGuire was propelled into the position three weeks ago after serious injuries to Brett Seymour (knee) and Shaun Berrigan (hamstring) and turned in one of the best displays of his young career.

The versatile 24-year-old set up both of Brisbane's first-half tries with clever runs to keep the Broncos in the game before Stuart Kelly's try in the 69th minute sealed the two points.

Brisbane coach Wayne Bennett praised the efforts of McGuire and halves partner Ben Ikin over the last month.

"I'd certainly like to give credit to Casey and Ben Ikin," Bennett said.

"They've certainly been good for us in the last two weeks."

Bennett added that the win was made easier with only five players backing up from Wednesday's opening State of Origin clash.

"We only had five backing up so that was a real bonus for us so it made it very manageable," he said.

Embattled Dragons centre Mark Gasnier scored two tries in his first NRL game since being dumped from the NSW State of Origin squad but his efforts alone weren't enough to get the visitors home.

Gasnier's successful return came at the end of the most turbulent week of his career.

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