Erakovic, the No. 4 seed, had won no more than one match in any of the five previous tournaments in which she had played this year.
She earned a spot in the semifinals by disposing of Krajicek 6-4, 6-7 (2-7), 6-4.
Vera Dushevina will meet Erakovic in the semifinals after downing Stephanie Foretz Gacon 3-6, 6-3, 6-1.
Friday's other semifinal will send Sofia Arvidsson against Alberta Brianti. Arvidsson outlasted Lesia Tsurenko 6-2, 7-6 (11-9) and Brianti was a 7-5, 6-3 winner over Varvara Lepchenko.
No. 1 seed Nadia Petrova did not make it out of the first round and second-seeded Ksenia Pervak fell to Brianti in the second round.