Both players gain first England starts on Saturday since the 2005 Six Nations Championship.
Jones was an integral part of Sale Sharks' stirring Guinness Premiership title success this season, while World Cup winner Kay's return to form with Leicester saw a drifting talent resurrected.
"Ben and Chris have had very good seasons for their clubs," said England forwards coach John Wells.
"Ben's experience is tremendous, and I believe he will put a lot of pressure on Australia this weekend."
As for Kay's post-2003 World Cup drift towards anonymity, Wells added: "The World Cup affected a lot of guys.
"Some retired, some lost form, but when he came home - like a few of the squad - Ben had different agendas.
"He lost his place at Leicester and he got a kick up the backside and has had to earn his recall at the club, never mind England."
Jones, meanwhile, has worked hard on his tight game, bulking up in the process and piling on poundage for the heavyweight confrontations that exist throughout Test rugby.
"Chris has a terrific attitude towards his desire to playing at this level," said Wells.
"I believe he has turned from being a quick, fast-running back-row forward into a hard-nosed second-row operator. He has bulked up, and he has done very well for Sale in their title-winning season."
Jones and Kay will be part of an England pack that must match the Wallabies blow for blow at Telstra Dome, otherwise a 13th defeat from 15 starts against them Down Under beckons.
Full-back Iain Balshaw and wing Tom Varndell remain key strike weapons, with attack coach Brian Ashton also backing fly-half Andy Goode's appearance for what will be only a second Test start.
"Iain is an outstanding player who needs games," said Ashton.
"He has had some injury problems and hasn't played that much, but I believe full-back is his natural position. His ability to read and hit space, if you watch him from behind the posts, is second to none.
"Andy Goode is a confident sort of player. I have been talking with him, and I am convinced he will handle the pressure very well.
"With Tom Varndell, he has only just turned 20 and there are areas of his game he will be the first to admit he needs to improve, but he also has what most others in world rugby don't have - absolute blistering pace."