Suliasi Vunivalu hobbled off with a hamstring injury as an already undermanned Queensland Reds fell 31-24 to the Blues in Super Rugby Trans-Tasman.
Hunting a Test debut next month, NRL convert Vunivalu limped off Suncorp Stadium just a month after returning from another hamstring complaint in his maiden rugby union season.
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The Reds were already without late omissions James O'Connor (neck) and fullback Bryce Hegarty (hamstring) but had every chance to pinch rare back-to-back wins over New Zealand opponents.
Line-out woes cost them - they lost four in the second half - while the Blues scored twice while yellow-carded Brandon Paenga-Amosa was off the field in the first half.
Captain Liam Wright heaped praise on the teenager and Stewart, who had found a home in the centres after struggling in the No.10 as Quade Cooper's replacement in 2018.
The pair only found out hours before kick-off what Saturday night had in store for them."It's been a pretty crazy couple of days," Grealy told Stan Sport post-game.
"I was just sitting around today watching a bit of basketball with my roomies and got the call from Thorny (coach Brad Thorn).
"The first 15 minutes was a bit surreal ... but once that first kick was done it was just footy from there and I really enjoyed it."
Harry Wilson scored off a short inside ball from a heavily-involved Hunter Paisami, the pair standouts as the Reds looked to back up last week's breakthrough win over the Chiefs.
But a shot at their first back-to-back wins over New Zealand sides since 2013 came undone when Wilson opted to kick instead of pass to an unmarked Vunivalu. The ball skewed out and Vunivalu pulled up sore.
Fellow winger Filipo Daugunu scored from a cross-field bomb then nailed a penalty with one minute to go, the Reds unable to score after the buzzer to tie it up.
Blues skipper Patrick Tuipulotu and halfback Finlay Christie were influential for the Blues, scoring tries that followed first-half five-pointers to Dalton Papalii and Mark Telea.
A bonus-point win over the Western Force next weekend would secure the Blues their first final since 2003.
"We didn't want to let any excuses creep in tonight," Tuipulotu said.
"It would mean a lot - there hasn't been a home final for Auckland Blues for a while - that's in the back of our minds but we have to do next week first."
REDS 24
Tries: Wilson, Paenga-Amosa, Daugunu
Cons: Henry 3
Pens: Daugunu
BLUES 31
Tries: Papalii, Telea, Tuipulotu, Christie
Cons: Black 4
Pens: Black
