The world No. 2 shot two-over-par on the front nine at the Des Moines Golf and Country Club in Iowa to allow Team Europe opponent Anna Nordqvist to go four up and take what seemed to be an unassailable lead.
However, a pep talk from captain Juli Inkster at the turn proved to be the catalyst for an incredible comeback, as Thompson went on to shoot eight-under-par over seven holes -- including eagles on the 11th and 15th -- to ensure the point was halved.
"That was the weirdest round of golf I've ever played," Thompson told reporters
. "Front nine I don't think I was awake. And the back nine I just played lights out.
"Four down going into the back nine, I told myself I have to go all in -- and that's what I did. I shot a six-under total -- two-over for the front, eight-under for the back. Crazy."
Inkster made some personal history of her own by becoming only the second captain in history to win multiple Solheim Cups.
The seven-time major champion took over as captain for the historic comeback win in 2015, two years after Team USA had suffered back-to-back losses in 2011 and 2013.
"It helped me out a lot," Thompson said of her chat with Inkster. "I struggled with my first few holes. I don't really know what was going on.
"Having them there for me, picking me up, just telling me to keep my head up and that I'm the best, and I can do this. I can come back and make six birdies, seven birdies in a row.
"It means the world to me to have them there for me. And that's what this event is all about, to have captains and assistant captains like that."
Despite a wealth of experience and a winning debut as Team USA captain in Germany two years ago, Inkster admitted she felt some final day nerves heading into Sunday.
Team Europe would have had to have produced a miraculous comeback -- akin to their male counterparts in the Ryder Cup at Medinah in 2012
-- to claw back the 10.5 to 5.5 deficit.
"I really haven't been nervous all week but today I was a little bit nervous," Inkster told reporters. "You know what, this team just bonded. They believed in each other.
"They played for the person behind them and in front of them. And they played some amazing golf."
Lizette Salas eventually holed the winning putt in her match against Jodi Ewart Shadoff to confirm victory.
Europe captain Annika Sorenstam, though, was full of pride with her team's performance but admitted she had to concede defeat to the better team over the three days.
"We just got outplayed. There's no doubt about it," she said. "I'm so proud of how hard they fought. It's not easy coming out here on a Sunday with the team so far behind.
"I'm proud of them. They were out there fighting every single match, every single point. I congratulate the USA because they played some awesome golf."