He did that and then some, his confidence boosted by his birdie at the par-four seventh, where he struck a low fizzing pitch that scuttled into the hole.
"I lost a little confidence in myself and my game, and the ability to go out and get the win", Day said.
It's easy to overlook Leishman because the Australian has only two PGA Tour victories, including the Arnold Palmer Invitational earlier this year.
Leishman can not, however, boast the best halfway score ever at Conway Farms, an honour that belongs to Day, who plundered the layout two years ago on his way to a victory that vaulted him to number one in the world.
Day's sensational form on the greens is more impressive given he has hit just seven of 14 fairways and 10 of 17 greens in regulation. "Pushed it a little bit but I was trying to hit a high shot, 7-iron about 182 yards and land it there". He is on minus one after two rounds, well back on joint-clubhouse leader Jason Day.
One of those eagles was a chip-in from 30 feet from beyond the green at the par-five 14th.More news: 48 teams kick off Europa League with Champions League aim
For two days, he has looked like the Day of old. Last time I was here I was five shots better [after 36 holes].
Day still feels far away from 2015, when he won the PGA Championship and a pair of FedEx Cup playoff events.
Spieth heads the FedExCup standings -- and the race for the $US10 million ($F20m) bonus awarded to the overall season champion -- with only next week's Tour Championship in Atlanta remaining after this week. Leishman still clinging to that 2-shot lead at 17 under. Second-placed Thomas also carded 70 to fall 11 strokes behind. Rory McIlroy is at No. 51.
Marc Leishman left his clubs in the garage during his week break from the FedEx Cup playoffs and it didn't make a difference. Two weeks ago at the TPC Boston, he took a two-shot lead into the back nine only to get passed by Justin Thomas and Spieth by shooting 40 on the back nine to finish third behind Thomas.
It's certainly been a lean year for Day, one that started with him as the world's top-ranked golfer and saw him show up to this week's event without a spot in the Tour Championship assured. "I think everything's coming in bunches right now".