Kvitova, who picked up the title just a couple of weeks ago in Madrid, never looked entirely comfortable out on Court Philippe Chatrier, and was forced to draw upon all her fighting qualities to squeak past an often-inspired Erakovic, 6-4, 3-6, 6-4.
After nearly two and a half hours on court, Kvitova, who actually won seven fewer points than Erakovic, summoned her best tennis when she needed it most, finding the line with an angled backhand winner to break before calmly serving out to love.
"I think she didn't miss so much, and there were a lot of good rallies. It was really difficult," Kvitova said. "She's a really smart player with a good touch, so I knew it was going to be difficult.
"I played her last time here, as well, and it was two sets. But, anyway, every match is different. I'm just glad that I won."
It was clear from the opening exchanges that the No.4 seed was not going to have things all her own way. Erakovic threatened to break a couple of times, before striking at the third time of asking after another sloppy service game from Kvitova.
Although Erakovic failed to hang onto this advantage, Kvitova pinching the set from under her nose with a run of four straight games, she came roaring back to take the second in impressive fashion.
With memories of her four previous defeats to Kvitova perhaps lurking at the back of her mind, Erakovic struggled to maintain this level in the decider. Kvitova, too, was a bundle of nerves - fluffing one inviting volley with the court at her mercy at 3-3 - but steadied herself to eventually make it across the finishing line.
The heavy conditions made life difficult for Kvitova, who was particularly frustrated by her inability to pierce Erakovic's defenses.
"I have to say the conditions weren't really easy for me. I think it was quite cold and the balls are really heavy, and they didn't really fly," she added. "For me it was really difficult to go for the shots. It was tough to make any winners or ace from the serve or something like that.
"It was very difficult today. It was quite a long match, a big fight. Sometimes I couldn't win my serve. But that's how it is in the first round of Grand Slams. I'm just glad I'm still in and still playing."
Kvitova has an up and down history at Roland Garros, reaching the semifinals in 2012, but falling in the third round on her two subsequent visits. Next up this time will be Sílvia Soler-Espinosa, after she ended the hopes of Pauline Parmentier, 6-4, 6-3.