"At 3-1, I kind of found my way, found my rhythm, and I was striking the ball very well out there and took control of the points," said Jankovic.
"I just did not let her play what she plays. That was very important. So I was pretty pleased with the way I played and how composed I stayed throughout the whole match."
Italian qualifier Camila Giorgi came back down to earth with a thud when she was thrashed 6-2 6-1 by compatriot Flavia Pennetta less than 24 hours after she stunned Maria Sharapova.
"I just tried to do my game, play aggressive and play fast," said Halep, ranked seventh in the world. "It wasn't my best tennis today, but I was fighting a lot. I did well.
"I think I came back in the third set really well. I did everything I could do during the match today."
BNP Paribas Open results
17-Sloane Stephens (U.S.) beat Alisa Kleybanova (Russia) 6-3 7-5
12-Dominika Cibulkova (Slovakia) beat 8-Petra Kvitova (Czech Republic) 6-3 6-2
2-Agnieszka Radwanska (Poland) beat 22-Alize Cornet (France) 7-5 6-3
20-Flavia Pennetta (Italy) beat Camila Giorgi (Italy) 6-2 6-1
7-Jelena Jankovic (Serbia) beat 10-Caroline Wozniacki (Denmark) 6-3 6-1
Casey Dellacqua (Australia) beat Lauren Davis (U.S.) WO
6-Simona Halep (Romania) beat 18-Eugenie Bouchard (Canada) 6-2 1-6 6-4
- Sports & Recreation
- Agnieszka Radwanska
- Simona Halep
- Alize Cornet
- Dominika Cibulkova
- Petra Kvitova
- Flavia Pennetta
- Camila Giorgi