Both players came into Ningbo on highs - Jovanovski won her second WTA title two weeks ago in Tashkent, Zhang her first WTA title last week in Guangzhou - and both reached another final here.
After winning a marathon 71-minute first set - even saving a set point down 6-5 in the tie-break - Zhang looked headed for victory as she built an early 2-0 lead in the second set. But Jovanovski had been in that situation already this week and come out of it, having come from 64 53 down to win her semifinal match, and the No.1-seeded Serb did it again, taking 12 of the next 15 games to win, 67(7) 64 61.
"Zhang Shuai is a great player - she played great this week and the tournament before in Guangzhou too," Jovanovski said. "I think it was a really difficult match today. It's really tough to play against a friend. I was just trying to be fair on the court and play my game, and I'm happy to win this title.
"I was maybe just a little bit better and had a little bit more power in the end. But she played great."
Jovanovski now has a WTA 125K Series title to add to her two WTA titles (Baku last year and Tashkent this year). She will now head to the China Open in Beijing, where she plays Sorana Cirstea first round.
Zhang did return to the court a little later on though, and came out on top - seeded No.1 with Chan Yung-Jan, they beat No.4 seeds Irina Buryachok and Oksana Kalashnikova for the doubles title, 62 61.
Ningbo was the third WTA 125K Series stop of the year, following Cali, Colombia in February (which was won by Lara Arruabarrena) and Suzhou, China in August (which was won by Shahar Peer). There are two more WTA 125K Series events to come this year - Nanjing, China and Taipei, Chinese Taipei.