After winning a routine first set and winning the first game of the second set, Kerber watched on as her opponent, Peng Shuai, reeled off 11 of the next 13 games to take that second set, 6-1, and build a 5-2 lead in the third. But the No.5-seeded Kerber clawed her way back and snuck it out, 63 16 76(5).
Pironkova leads Kerber in their head-to-head series, 2-1, and has actually won their last two meetings in straight sets - including right before the Australian Open earlier this year in the Sydney finals.
Elsewhere, Flavia Pennetta - who shot up to No.12 in the world this week after her triumph at Indian Wells but is seeded No.20 because the seeds were based on last week's rankings - overcame a bit of a slow start, losing the first two games, but cruised past Belarusian qualifier Olga Govortsova, 63 63.
"It was a tough match, but I think we played good tennis," Pennetta said afterwards. "It was not easy to stay focused on the new tournament, but I did my best and everything was working pretty good."
Pennetta scored the 10th and biggest WTA title of her career last week at the BNP Paribas Open, which is also a Premier Mandatory event, and she seems to have brought that form to Miami.
The Italian talked about the dangers of dwelling on victories after her big triumph on the weekend.
"Tennis gives you good moments, but they can be really short," she said. "You never really get to enjoy them a lot because the day after you have to go back on the court and play another match."
Indian Wells wasn't the first huge revival for the former World No.10 - Italy's first Top 10 player, in fact - she also made a Cinderella run to the US Open semifinals last summer and again to the Australian Open quarterfinals earlier this year. She seems well on her way to the Top 10 once again now.
"I remember after the match with Francesca at Indian Wells last year, the day after I was in the garden and talking with my physio, almost crying because the feeling and everything was so bad," she said. "Now, after one year, we have this trophy. We worked so hard after the injury and everything. Without him, without my coach, without my family, maybe I wouldn't be here - I mean I would've quit.
"Until Wimbledon it was really tough. It was a bad year. I was really close to stopping. But after Wimbledon I started feeling a little bit better, and since then everything is coming. I've worked so hard and everything has been coming out in the last seven, eight months, and I'm just really happy."