And with that deadline now fast-approaching, the Wallaby boss admits he is in near constant contact with those players currently sidelined through injury.
Prop forwards Benn Robinson (knee) and James Slipper (ankle), hooker Tatafu Polota-Nau (knee), No8 Wycliff Palu (knee), centre Rob Horne (elbow) and wing Drew Mitchell (ankle) are all desperate to convince Deans that they will be ready for the tournament opener against Italy on September 11.
"It's come around very quickly," said Deans, who is highly unlikely to be able to select any of the six aforementioned players for Saturday's Tri Nations clash with South Africa in Durban.
"It's not going to be easy, and there'll be pain as there always tends to be, but some good players are going to miss out this time.
"We had a conversation last night with a few (injured players) and we had one today with some we missed yesterday. They're all working hard. As you do with rehabing, some have encountered speed bumps, but there's nothing grave.
"They're all pushing the boundaries because they all desperately want to be involved. They're aware that when we get back (from South Africa) we'll finally test them on the Wednesday and the team's named the next day.
"So there'll be a fair amount of anxiety over there, I'd suggest. Hence the need for so much communication."
Australia host New Zealand in their final Tri Nations fixture of the year on August 27, before taking on Italy, Ireland, USA and Russia in Pool C of the World Cup.
Of the six injured names looking for a place in the final 30, Robinson and Mitchell are likely to be giving Deans the most sleepless nights as the Waratahs duo would both be in his first-choice starting XV.
The remaining four players would all be likely members of the wider party if fit, meaning pressure will be on a range of current fringe players to prove their worth if givEN a shot against the Springboks.
Back rowers Matt Hodgson and Ben McCalman, second-rowers Sitaleki Timani and Radike Samo, hooker Saia Faingaa, props Pek Cowan and Salesi Ma'afu, wing Lachie Turner and centre Anthony Faingaa all have something to prove, as do experienced playmakers Matt Giteau and Berrick Barnes.