The 57th-ranked Wozniak trailed 4-1 in Sunday's opening set against El Tabakh. But the Toronto resident, ranked 183rd in the world, missed on three nervous set points and was broken in her last two service games as Wozniak turned the momentum.
The Blainville, Que., native rolled through the second set against El Tabakh to move onto the second round at Roland Garros for the fifth straight year.
"I don't like playing Heidi. I remember when we were juniors and travelling with our moms together. She also came with a lot of energy to the court," Wozniak said. "After I saved those set points I adjusted my game, I started moving her around more. In the second set the match totally changed, it was a completely different match."
El Tabakh said she had her chances with the set points, but let them get away.
"She ripped a few shots and I made some errors. I got tight and once she won the set she picked up her game," El Tabakh said. "I didn't even think I'd be in (qualifying) here, so it's all a bonus."
Earlier Sunday, the first two Canadians on court lost their opening matches, with Vasek Pospisil admitting he's burned out on the clay.
The Vancouver resident made a promising start but fell 3-6, 6-3, 6-2, 6-2 to Edouard Roger-Vasselin of France.
"I started pretty well and had good momentum," Pospisil said. "I played a pretty decent second set and had chances after that.
"But the crowd was into it and I didn't get my intensity up. It's tough to play a French guy here. I had maybe a week too much on clay, the surface which is my least favourite."
In women's play, Israel's Shahar Peer defeated 98th-ranked Stephanie Dubois of Laval, Que., 6-2, 6-2.
Pospisil, ranked No. 102, won the first set in 40 minutes but could not keep pace as the match wore on.
He saved four match points in the fourth set before ending his debut at Roland Garros on a wide forehand for his 55th unforced error.
"I've had two months on clay and I'm not that excited about it right now," said Pospisil. "I burnt myself out last week in Nice (in a first-round qualifying loss) when I thought I was playing pretty well.
"I'm ready for a change of surface."
On Monday, 19th seed Milos Raonic of Thornhill, Ont., is schedule to open his tournament against Spain's Ruben Ramirez Hidalgo while Frank Dancevic of Niagara Falls, Ont., is slated to take on Slovakia's Martin Klizan.