After ousting No.3 seed Venus Williams in the semifinals the day before, Jankovic had the difficult task of pulling off back-to-back upsets on back-to-back days as she had to take on No.1 seed Angelique Kerber in the final. And for two grueling hours the top-seeded German was in control, even on the brink of victory - she was up 6-3, 6-5, just a game away from winning her fifth WTA title of the year.
But the No.4-seeded Jankovic held her ground, held at love to push the second set to a tie-break, won the tie-break and only got better from there, rolling to victory in the third set, 3-6, 7-6(4), 6-1.
This is Jankovic's second WTA title of the year, having won Guangzhou a few weeks ago. It's actually the first time the Serb has won two WTA titles in the same year since 2009 (Marbella and Cincinnati).
Additionally, it's the milestone 15th WTA title of the former World No.1's illustrious career.
On the other side of the net, Kerber wasn't just a win away from her fifth WTA title of the year - had she won, she would have qualified for the BNP Paribas WTA Finals Singapore presented by SC Global.
"I had an amazing week in Hong Kong," Jankovic said at the trophy ceremony. "It's been unbelievable - Hong Kong is such a beautiful city, it's my second time here and I'm really falling in love with it.
"And Angie, thank you so much for letting me win today! You've beaten me so many times, so I'm happy I could finally do it. You're an amazing competitor and fighter and I'm sure we'll play again soon."
"First of all I want to say congratulations to Jelena for a great week," Kerber said. "I tried as hard as I could. I was fighting until the last point. Some days you have a little bit of pain everywhere in your body, but I was really just trying my best until the end of the match. Jelena just played too well tonight."
Both finalists had only good things to say about the incredible crowds that came out during the week.
"Without you, this tournament wouldn't be as special as it is," Jankovic told the fans. "Thank you so much for coming out throughout the week and filling up this stadium - tonight was almost a full house! It was an amazing atmosphere and an amazing energy, and hopefully we will see you all next year."
"Thanks to all you guys," Kerber said. "Thank you for your support the whole week - I was trying as hard as I could and you really helped me keep fighting out here. I hope to see you all next year!"
? WTA (@WTA) October 18, 2015