The world No.112 was also a break down at 1-3 in the decider but played some scintillating shots to overpower the top seed in two hours and 30 minutes.
It was in stark contrast to her 6-2, 6-1 dismissal at the hands of Zvonareva in Madrid qualifying earlier this month.
“It could have been the same story today, it was a bit of a miracle. I think I played really well, she’s one of the most difficult players I could have faced this week,” the Slovakian said.
“I was brave, played my game and it’s one of the best matches I’ve ever played, it was such a big fight.”
>> ORDER OF PLAY: FRIDAY MAY 28
Schmiedlova achieved her joint-best showing at a Grand Slam in Paris last autumn, reaching the third round off the back of two standout wins.
“When I was a junior I played finals here (2012) and more recently I won some of the biggest matches of my life here last year, beating Venus (Williams) and (Victoria) Azarenka. Every year it seems special here,” she said.
“I’ve played on all the show courts here, that hasn’t happened at the other Slams.
“I don’t think I’ve ever played on such a beautiful arena as Philippe-Chatrier. It’s my favourite centre court ever. I’d love to play there or the beautiful Court Simonne-Mathieu again.”