The West Yorkshire club opted against appealing Chase’s two-game suspension for a reckless strike which knocked out Leeds Rhinos’ Zak Hardaker in Sunday’s 14-12 win.
But that decision clearly left them short of creative options ahead of tomorrow evening’s televised game at Bradford Bulls, meaning head coach Ian Millward has now delved into the transfer market.
Goal-kicker O’Brien, 21, made 10 Super League starts for the beaten Grand Finalists last season and also featured on loan at Widnes Vikings, making some notable impressions.
It is only the continued excellence of Warrington’s talismanic Lee Briers and England scrum-half Richie Myler that has denied him amassing even more appearances with the Challenge Cup holders.
O’Brien played on a dual-registration for Championship club Swinton last weekend but Millward was thrilled to give him a chance back in the elite and he will debut at Odsal.
“I have been an admirer of Gareth’s for some time and (Warrington coach) Tony Smith speaks highly of him as both a person and a player,” he said.
“Warrington currently have no injuries in their half-backs so they were happy to loan him out and give him some good playing experience.”
Sydney Roosters have, as expected, completed the signing of ex-Australian Test back-row Luke O’Donnell on a 12-month deal following his release by Huddersfield Giants.
The 32-year-old becomes the Roosters’ fourth close-season recruit, joining Sonny Bill Williams, James Maloney and Michael Jennings.
Leigh Sports Village has been chosen as the venue to host the 2013 Kingstone Press Championships Finals Day on Sunday, September 29.
The event has been held at Warrington’s Halliwell Jones Stadium for the last five years but, as has been the case with the Northern Rail Cup final, it is now on the move.