No. 4-seeded Li won the first give games to set up a 6-2, 6-4 win over 19-year-old Canadian Eugenie Bouchard in the first semifinal Thursday before No. 20-seeded Cibulkova trounced 2012 Wimbledon finalist Agnieszka Radwanska 6-1, 6-2.
Li, the 2011 French Open champion, was the only major winner in the semis after the fourth-round upsets of Serena Williams and Maria Sharapova and defending champion Victoria Azarenka's quarterfinal loss to Radwanska.
Cibulkova has been the biggest surprise of the tournament. The diminutive Slovakian has won all but one of her matches in straight sets -- her win over Maria Sharapova went to three.
She completed three of those wins in an hour or less, including her 6-3, 6-0 quarterfinal victory over No. 11 Simona Halep.
But even Cibulkova was stunned that her first win in a Grand Slam semifinal took only 1 hour and 10 minutes. After Radwanska held in the third game, Cibulkova won the next eight in a dominating roll.
"To tell you the truth yes because Aga she's an unbelievable player, her defense in the game is unbelievable," Cibulkova said. "It will be my first final I just want to enjoy it, like I have every match here."
Touted as the shortest women in the top 50 at 5-foot-3, Cibulkova has shocked her bigger rivals with the power in her ground strokes.
"It's something inside of me, I was born with it," she said. "It's my gift -- that's how I play."
The win was a significant upset only a day after Radwanska outplayed No. 2-ranked Azarenka, who won the previous two Australian titles.
Cibulkova had lost her only previous semifinal at a major -- at the 2009 French Open -- and had lost four of her five previous tour-level matches against Radwanska, including a 6-0, 6-0 defeat in the Sydney final last year.
Li lost last year's Australian Open final to Azarenka, after falling over and hitting her head twice on the court. She lost the 2011 decider to Kim Clijsters.
"I think is the third time, so pretty close to the trophy," Li said. "Yeah, at least I try to not fall down this time, because last year in the final I think I played well but I only can say I was unlucky. At least I'll try to enjoy and stay healthy."
Li raced out to a 5-0 lead in 14 minutes against Bouchard while people were still entering Rod Laver Arena.
Bouchard had a lot of support in the crowd -- there were people with Canadian flags painted on their faces, and a couple even wearing the national hockey jerseys.
Her own personal cheering section, the "Genie Army," serenaded her throughout the match, at one point competing directly with a group of Li's supporters across the stadium who chanted "Let's Go Li Na" in Mandarin.
Bouchard was playing only her fourth Grand Slam tournament, was seeded 30th and became just the second Canadian to reach a major semifinal.
"I think maybe she will be best player in the world. But today (I'm) so lucky," said Li, who jokingly apologized to the Genie Army. "Sorry about that. If you guys be happy, I will go home."
Li considered quitting the tour after the French Open last year, when she was beaten in the second round and was struggling with the off-court pressure. After reaching the quarterfinals at Wimbledon, the Chinese star opted against retiring and then reached the U.S. Open semifinals. Li, who turns 32 next month, has gone another step further in Australia.
After saving a match point in the third round against Lucie Safarova, she has started all her matches aggressively.
It worked against Bouchard, who didn't win a point in her first three service games. In the second set, the pair exchanged four service breaks in the first six games before Li finally took charge.
The next rankings list will reflect a big jump for Bouchard, who was one of the few people unsurprised by her rapid improvement.
"I wouldn't say I exceeded my expectations, but I'm happy with how I did," Bouchard said. "I always want to do better. To me it's not a surprise. I've been working hard my whole life to do this -- play at Grand Slams and do well. It's not an overnight thing."