Ivanovic had won both of her Fed Cup matches at the very same venue on the weekend and continued the pattern in the first round of the Premier-level event, getting broken by Petkovic at 1-all but then winning 11 of the next 13 games - and holding the rest of her seven service games - to cruise on.
"It was like a continuation of Fed Cup, playing against Germany," Ivanovic said after the match. "It was a very tough match today. Andrea is definitely a good friend of mine and it's never easy to play a friend, but I really tried to focus on my game and I served well, which made a big difference in the match."
"At the moment I'm lacking consistency," Petkovic said. "I wanted too much and that led to me taking far too many risks. But it was totally amazing out there - the atmosphere was cool, just like it always has been, and I've now replaced the negative experiences from last year with a positive one."
A former World No.9, Petkovic is trying to work her way back up the rankings these days after an injury-marred 2012 and a few injuries to start 2013 as well. "It's no problem. I'll also be playing the smaller events. I simply need matches," she said. "I just want to improve and keep playing more matches."
Petkovic still had some time for humor, though, about playing doubles this week with Angelique Kerber. "We're the two worst doubles players in the world. We'll try to win a few games," she said.
Ivanovic, however, moves on, and talked about her love for the tournament. "I think this tournament is many players' favorite," the former World No.1 said. "I love it. It's so nice to have everything in one spot. The hotel is close by, there's great food, a great court and a really fantastic atmosphere.
"It's always a pleasure coming here."
The home crowd had something to cheer about later on, though, as Sabine Lisicki overpowered Italian qualifier Nastassja Burnett, 63 64, coming out firing - she won the first five games of the match - and finishing strong too, winning the last three games of the match. The German blasted five aces.
There was some drama in the first set, though - Lisicki watched 5-0 become 5-3 before closing it out.
"She was starting to play some great points at the end of the first set and I was backing off a bit, I think," Lisicki said. "Luckily I was able to stop her after three games and close the set out."
Like Ivanovic, Lisicki is coming off a confidence-boosting weekend in Fed Cup - alongside Anna-Lena Groenefeld, she scored the decisive point in doubles in Germany's World Group play-off victory.
"I love playing doubles," she said. "Obviously in Fed Cup on the weekend it was a very important match we played, and playing at home made it even more special. So I always enjoy playing doubles.
"The fans here in Stuttgart are amazing, as they were on the weekend. I love playing for them."
Lisicki's second round opponent will be the winner of Wednesday's match between No.6 seed Samantha Stosur and Jelena Jankovic. "That's a great match, actually!" Lisicki said. "I love those kinds of matches. Both players are great players - Sam won a Grand Slam and Jelena was No.1 in the world. So it's going to be a tough match for me no matter who wins. I'm sure the crowd will be amazing."