Jones, who was born in California and lives in Atlanta, is looking to become the first American to win on the LPGA Tour in 2001.
'I am going to take it. I am going to take it for U.S.A.,' said Jones, who turned in a 2-under 68 at the par-70 Onion Creek Club. 'I am going to get it over with.'
But first Jones will have to contend with Baena and two other international players, Korea's Mi Hyun Kim and Canadian Lorie Kane. Kim, a three-time winner on the tour, posted a 64 of her own for solo third place at 8-under, while Kane, who captured her fourth LPGA title at the Takefuji Classic in February, finished the day alone in fourth with her second straight 68.
Baena, who joined the LPGA Tour in 1999 after an impressive amateur career that included a runner-up finish in the 1996 U.S. Amateur Championship, kicked off a sizzling front nine Saturday with a seven-wood to four feet for a birdie at the 1st.
After rolling in a 15-foot birdie at the 3rd hole, Baena wedged her third shot at the par-5 7th to within two feet to climb to 3-under on the day.
She holed out a bunker shot for a birdie at the 8th, then made it three in a row with a 15-foot birdie putt just before the turn. The 23-year-old Baena sank a four-foot birdie at 16 for her lone birdie against eight pars on the homeward nine.
'I dont think I have played better golf in my life,' said Baena, who credited her new coach with her improved swing. 'It seems like it is just much better consistency through my clubs.'
Baena, who played collegiately at the University of Arizona, has notched five top-10 finishes in three seasons, with the most recent a fourth-place showing at the Memorial of Naples event in January. She is still in search of her first victory.
'I am hitting so solid right now that I feel very confident that I am going to go tomorrow and hit good,' she said. 'I really feel that you need to be smart out there. Think where you want to hit it and be on the green and just hope you make your putt.'
Jones, a 10-time winner seeking her first victory since the 1999 Firstar LPGA Classic, came into round three with a two-shot lead but was shaky at the start with bogeys after missed greens at the 4th and 6th holes. She gave herself a pep talk after she missed the green at seven and saved par.
'I was still trying to settle down and just kind of get off that bumpy roller coaster that I was on,' Jones said. 'I was just trying to get where I had a couple of easy pars and then settle in a little bit.'
After racking up four more pars from the 8th to the 11th, Jones started heading in the right direction with a 12-footer for birdie at the 12th. She added birdies from 25 and 15 feet at the 13th and 14th, then made it to 2-under on the day after a 9-iron to three feet at 16.
Kim, whose best finish of the season was second after losing to Annika Sorenstam in a playoff at The Office Depot two weeks ago, closed out her bogey-free round with birdies at 16 and 17.
Kane, currently two back at 7-under, birdied four of the first five holes Saturday to move atop the leaderboard at 9-under par. However, a tee shot behind a tree led to a bogey at the seventh and she dropped another shot on 13 when she missed a four-foot par putt.
'I would like to be in the last group tomorrow, but I am also happy where I am. I don't mind chasing,' said Kane, who has won three of her four titles in come-from-behind fashion. 'I like putting some numbers on the board and having them watched.'
Dottie Pepper also has a chance to help the American cause on Sunday. The 17-time LPGA champion jumped into fifth place at 5-under 205 on the strength of a 68 comprised of three birdies and one bogey.
Se Ri Pak, the winner of last week's Longs Drugs Challenge in California, was forced to withdraw Saturday due to a neck injury.
Full-field scores from the Kathy Ireland Championship