Ivanovic books place in semis
Serb Ivanovic sent number four seed Peng packing in the late game at La Costa Resort and Spa after the top three seeds had earlier progressed from their quarter-final matches.
Zvonareva shrugged off six double-faults to overcome the German in a tight match which lasted two-and-a-quarter hours.
And in Saturday's other semi-final, second seed Andrea Petkovic, who ended home hopes with a 6-2 6-1 demolition of American Sloane Stephens, will meet third seed Agnieszka Radwanska, who put out Daniela Hantuchova of Slovakia 0-6 6-4 6-4.
Petkovic was imperious against teenager Stephens, who finally looked out of her depth after a decent run at the tournament that saw her reach her first quarter-final on the WTA Tour.
"It's very important when you play these young players to show who's the boss on the court," Petkovic said.
"There will come another time and another place when she will be a top player."
Radwanska struggled with a shoulder problem in the first set against Hantuchova, dropping it to love, but she overcame her difficulties in the next two sets to see off the eighth seed.
The Pole admitted she considered retiring after the opener, but the thought of a double bagel defeat spurred her on to turn the match on its head.
"You're playing Daniela, who is a great player. I could lose the match, but not 6-0, 6-0. I've been playing too well to lose so quickly," she said.
"That pushed me to keep fighting."