Heather Knight's team were 6-0 down in the multi-format series after losing both the lone Test and the first Twenty20 international against double white-ball world champions Australia.
But they have fought back impressively to be all square at 6-6 following a two-wicket win in the first one-day international in Bristol on Wednesday.
Victory in the second ODI at Hampshire's Ageas Bowl headquarters on Sunday leave England just a win away from regaining the Ashes for the first time since 2014 and inflict a first ODI-series defeat on Australia in a decade.
Jones, however, insisted England would still retain the "underdog" mentality that has served them well in recent games.
"I think everyone is feeling pretty relaxed," she told reporters on Saturday. "We had a good review of the game, looking at areas where we can improve still, which was really motivating as a group after a win.
"We've obviously got an opportunity to win the ODI series tomorrow so everyone is pretty excited about it."
The 30-year-old, who had the unenviable task of succeeding England great Sarah Taylor behind the stumps added: "We've gone the whole series feeling like underdogs and we're just trying to keep that mentality of acknowledging how good a side Australia are, but sticking to our strengths and trying to put them under as much pressure as possible during the game.
"It will be a similar mindset tomorrow I think.
"I think there was more pressure when we were 6-0 down than there is now."
The series concludes with the third ODI at Taunton on Tuesday.
