Wozniacki broke Jankovic's serve five times Saturday in a 6-4, 6-4 semifinal victory at the Family Circle Cup. Also demoralizing, Jankovic acknowledged, were the extended rallies on the green clay court.
"She always makes you play an extra ball," Jankovic said.
The 20-year-old Dane had escaped her past two matches, winning two tiebreakers against Barbora Zahlavova-Strycova on Thursday and overcoming a 4-2 deficit in the third set to beat Yanina Wickmayer in the quarterfinals.
Wozniacki knew she couldn't start that slowly again and make it through.
"I had to be aggressive and hit it deep because [Jankovic] is such a good fighter," she said.
That was apparent as the two traded line-drive groundstrokes throughout the nearly two-hour match on the windy stadium court at the Family Circle Tennis Center.
The first three games all went to deuce. Jankovic led 4-3 in the first set before Wozniacki rallied to take the final three games, breaking her opponent twice in that stretch.
The back-and-forth resumed in the second set until the ultra-steady Wozniacki pounced on her opponent's errors. Tied at 4-all and up 30-love, Jankovic gave away the next four points, three on balls hit long and one hit into the net.
Jankovic sailed the ball long on match point.
"Some other players, you think it will be a winner," Jankovic said. "With her, it somehow comes back."
Wozniacki and Jankovic share similar styles and frustrations at times. Wozniacki said balls she's accustomed to watching go for winners were hit back.
"So I think we were pretty even," Wozniacki said.
Vesnina, 56th in the world, defeated China's Peng Shuai 7-6 (4), 6-3 to advance. Vesnina had considered skipping Charleston a month ago because of continuing problems with her wrist.
A technique change suggested by her father and coach, Sergey Vesnin, helped relieved the pain and Vesnina entered. It was a good decision.
Vesnina hadn't been past the quarterfinals in five previous appearances and beat four seeded players, including No. 5 in world Samantha Stosur, to reach her first singles final of the season.
"I'm telling you, I'm just enjoying my time on the court," she said.
Next up is the toughest out of all in Wozniacki. The two finalists have played five times with Wozniacki winning all but one.
"I know her game pretty well," Vesnina said. "And it just depends how I feel, how Caroline will play tomorrow."
Wozniacki was guaranteed to remain No. 1 through May 16 no matter what happened in this tournament. Still, she's pleased with her success at her first clay-court event.
"I'm just happy to be in the finals again," she said. "It's been a great week for me."