That leaves Phipps, Australia's incumbent No.9, as the frontrunner to start against Fiji despite being in and out of the Waratahs side - and below his best - over the first 10 rounds of Super Rugby.
He missed two games through injury early in the campaign before being dropped to make way for Jake Gordon, who has been reinstated to start against the Blues despite Phipps' impressive display in the Waratahs' weekend win over the Queensland Reds.
"Jake's been very good for us. Right now I still believe he's the No.1 halfback," Gibson said on Thursday.
"Nick is closing the gap. There's no doubt about that and that was probably one of his best performances (of the season last Saturday).
"We've employed a policy of rotation. We want to give all our halfbacks an opportunity to show their best and Nick had an opportunity last week and now Jake returns and gets his chance."
Cheika has been a keen observer of Phipps' "chequered start to the year", but indicated last month he was leaning towards sticking with him for the Fiji Test.
"I know that Nick has got a certain skill set that he's very good at and when he gets back to doing that skill set alone, and focusing just on that, that he'll be back right in the reckoning," Cheika said.
The coach added that he wasn't obsessed with picking club combinations, even though the NSW duo of Phipps and Bernard Foley looms as his likely first halves pairing employed for the Wallabies this year.
"In 2015, everybody was saying it's got to be either Phipps and Foley or Genia and Cooper and then we went Genia and Foley and they went pretty good together," Cheika said. Gordon is certainly not out of the running for a debut against Fiji after Cheika drafted the 23-year-old into a three-day Wallabies camp last month.
- AAP