The Australian pair were mighty in giving the Internationals a golden opportunity to win the Cup for the first time since 1998.
In a repeat of Montreal two years ago, Geoff Ogilvy's underdogs claimed all five points on day two in Illinois.
"It was an incredible day for us," International team captain Ogilvy said."We did it in Montreal, so maybe it's a pattern now. We never mentioned that, but the boys played really well."
Scott had his long wand weaving magic in teaming with South African Christiaan Bezuidenhout for a 3 and 2 win over Justin Thomas and Cameron Young.
Lee partnered New Zealand Cup debutant Ryan Fox to a clutch 1 up win over the American pair of double major winners Collin Morikawa and Wyndham Clark.
Reigning Open champion Fox sealed victory on the 18th green after Lee's supreme driving proved a feature of the day at Medina Country Club.
Canadians Corey Conners and Nick Taylor set the tone for the Internationals with a nerve-shredding 1 up win over world No.1 Scottie Scheffler and Sam Burns.
Clinging to a one-hole lead heading up the last hole, Taylor's errant drive placed the duo under extreme pressure but he replied with a magical approach to two feet after Conners was forced to lay up 148 yards short of the green.
Conners duly holed the putt to leave tie the scores up at 3-3 after Team USA won three of the five day-one fourball matches.
A 4 and 3 victory for Tom Kim and Si Woo Kim over Xander Schauffele and Patrick Cantlay and a 3 and 2 win for fellow South Korean Sungjae Im and Japanese superstar Hideki Matsuyama over Russell Henley and Jacob Bridgeman completed only the Internationals' second-ever foursomes whitewash.
"Obviously it's an exciting day for us, but if we take something from Canada, it's not to celebrate too hard at this point. We're not even halfway through this tournament so there's a long way to go, but it's a great day for our team," Scott said."I think we should embrace what happened here today and kind of look forward to tomorrow."From where I sit, if any of the guys were lacking belief, they should have it now going into the weekend."
With 20 points still up for grabs, the 13th edition of the Presidents Cup is realistically only one-third through.
But the Americans will still need to collect 12.5 points from the remaining three sessions to pull off a comeback victory.
There will be eight more team matches on Saturday (Sunday AEST) before 12 last-day singles encounters.
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