Halep, who already had three Top 10 wins to her name - Li Na in 2011, Agnieszka Radwanska and Marion Bartoli earlier this year - calmly stormed past Wozniacki in the first set, belting backhands and curling forehands into the corners to clinch it in 33 minutes, 6-2. Her numbers were extremely clean - she hit 13 winners to 7 unforced errors, with Wozniacki a less favorable 4 winners to 8 unforced.
After dropping serve in the first game of the second set Wozniacki picked up her level, breaking right back and even getting slight leads midway through the set - she led 4-3 and 5-4, even getting within two points of winning the set at 5-4. But Halep held, broke one last time and served it out, 62 75, finishing the No.4-seeded Dane off on her third match point on a crosscourt backhand winner.
"I'm really, really happy that I won this match because I was nervous before the match - she's a top player," Halep said. "But I played really well. I started the match really well. She was playing good tennis but so was I, and we were just trying to do a nice match today because it was the semifinals."
Halep not only scored her fourth Top 10 win, she also reached her seventh WTA final, and second at the Premier level - she was a runner-up to Radwanska at Brussels last year. Additionally, the young Romanian has now won an impressive 28 of her last 33 WTA main draw-level matches on the tour.
"I have a lot of confidence right now," Halep said. "This has been a good period for me. I've been playing really well and feeling the game really well, and I'm enjoying myself on the court much more than I was before. I'm just trying to play my best every time I'm out there, which is very important."
Wozniacki, who won this tournament four years running in 2008, 2009, 2010 and 2011, now has to settle for her second straight semifinal finish at the tournament. She is 23-2 in New Haven now.
"She takes the ball really early," Wozniacki said. "She forced me to play some shots that I didn't want to play today. I tried to change my game up a little bit and tried to go for a little bit more, but today just wasn't my day. But she played really well. She definitely did. I felt like I made a few more unforced errors than I usually do, but I have to say it was because of her game and her level of play out there.
"It's a very empty feeling in a way because I've been so used to winning here, and I love winning. It's been so much fun, but then today I didn't win. So obviously it's a bit disappointing. At the same time, I've had a great run here for so many years now. As we've said, six years - time's really flying."
And will Wozniacki try to recapture that winning feeling here next year? "It's a tournament I love to play and a tournament I love coming back to," she said. "As I said on the first day, I hope the next four or five years we're still playing, and I can maybe retire here on these courts together with Anne."
Halep will play No.3 seed Petra Kvitova in Saturday's final - it will be their first meeting.
"I know she hits the ball very strong, but I haven't seen her play too much, so I will see tomorrow," Halep commented. "I will just try to stay calm. It's important to play relaxed because it's a final."