Victoria Azarenka had to endure some anxious moments before and after her win over American teenager Sloane Stephens.
Li Na wasn't flustered at all in an easy victory over No. 2-ranked Maria Sharapova.
The result is that Li will play for the Australian Open title against Azarenka, who ended Stephens' unexpected run to the semifinals that included a quarterfinal upset of 15-time Grand Slam champion Serena Williams.
Another player who had little trouble Thursday was defending champion Novak Djokovic, who looked like he was conducting a tennis clinic in overpowering No. 4 David Ferrer 6-2, 6-2, 6-1 in just 1 hour, 29 minutes.
"I played perfectly," he said in a post-match TV interview. "I played incredible tennis."
Djokovic will attempt to win his third consecutive Australian Open when he plays the winner of Friday's semifinal between Roger Federer and Andy Murray in Sunday's championship match.
While Li's 6-2, 6-2 win over Sharapova, who set a tournament record in dropping only nine games in five matches en route to the semis, never appeared in doubt on Thursday, Azarenka added some drama in the second semifinal on Rod Laver Arena.
Azarenka needed six match points to finish off a 6-1, 6-4 victory over Stephens that included a medical timeout after the American broke her serve to pull within 5-3 in the second set. After leaving the court for medical attention, the Belarusian returned to break Stephens' serve to end the match.
"Well, I almost did the choke of the year," Azarenka told an on-court interviewer immediately after the match. "At 5-3, having so many chances I couldn't close it out."
Australian Open officials said the tournament doctor reported that Azarenka had left knee and rib injuries.
"I just felt a little bit overwhelmed. I realized I'm one step away from the final and nerves got into me for sure," Azarenka said.
The 23-year-old Belarusian's on-court comments after the match led to speculation about the timing of her medical timeout. She didn't help herself in a second television interview after the match that suggested the pressure of trying to close out the match was getting to her.
"I couldn't breathe. I had chest pains," she said. "It was like I was getting a heart attack. After that it wasn't my best, but it's important to overcome this little bit of a struggle and win the match."
In her official post-match news conference — more than an hour after she finished playing — Azarenka felt a need to explain her comments immediately after the match.
"I think I just really misunderstood what (the on-court interviewer) asked me because the question was I had few difficulties and why I went off," Azarenka said. "I completely thought of a different thing, why I couldn't close out of match, you know, that I had few difficulties.
"So I understand the whole situation right now, but it just really (is a) simple misunderstanding of a question. I guess it was my bad."
Pressed again to explain her earlier TV comments, Azarenka said: "I did say that. I did say I couldn't breathe. It was locked. That came from my back. "
Stephens didn't think the timing of the medical break affected the outcome of the match.
"It's happened before. Last match, match before, I've had people going for medical breaks, going to the bathroom," she said. "Didn't affect me. Just another something else that happens."
The temperature hit 97 degrees during the second women's semifinal, slightly hotter than it had been when Li beat Sharapova to reach the Australian Open final for the second time in three years.
The semifinal started badly for the 25-year-old Russian, serving double-faults to lose the first two points and conceding a break in the first game.
Li was the first Chinese player to reach a Grand Slam final when she lost to Kim Clijsters at Melbourne Park in 2011. She had her breakthrough a few months later when she won the French Open, beating Sharapova in the semifinals along the way.
The crowd got behind Li early in the match, yelling "Come on, Li Na!" and others yelling "Jia You!" which is "Come on" in Chinese. After she broke Sharapova to take a 5-2 lead, the Chinese fans in the crowd shook Chinese flags and shouted again, "Jia You!"
"I don't know what happened, (but) I always play well here, so thanks guys," said Li, who was playing her third Australian Open semifinal in four years. "I just came to the court feeling like, 'OK, just do it.'"
Li's coach, Carlos Rodriguez, who worked with retired seven-time major winner Justine Henin, pumped his fist over his heart after Li won the game.
Sharapova had control in her next service game, but Li scrambled from side to side and pushed the reigning French Open champion to go for the lines, getting a series of unforced errors and another break.
The sixth-seeded Li has been working since August with Rodriguez, and credits him with reviving her career with a renewed emphasis on condition.
"I'm happy. I know I have a tough coach, a tough physio," Li said, looking across to the stands and adding: "You don't need to push me anymore. I will push myself."
Sharapova, who lost the 2012 Australian final in straight sets to Azarenka, admitted it was hard to get into the match against Li.
"She was certainly much more aggressive than I was, dictating the play. I was always on the defense," said Sharapova, who could have gained the No. 1 ranking by reaching the Australian final.
Djokovic was stretched to five sets in a 5-hour, 2-minute fourth-round match against Stanislaw Wawrinka, then lost a set against Tomas Berdych in the quarterfinals on Tuesday.
But the hard-serving Djokovic was at his sublime best on Thursday night, converting all of seven break-point chances while not facing any on his serve. Now unbeaten in five Grand Slam head-to-heads with Ferrer, he allowed his opponent only four points in the first four games of the last set.
"I felt very comfortable and very confident from the start," he said. "I wanted to be aggressive on the court. This is definitely one of the best performances I ever had in my career."
Ferrer double-faulted to set up match point, then lost the match on the following point when he floated a backhand long.
The Spaniard was pleased to have made it as far as he did in the tournament.
"I prefer to play worse in a semifinal than in the first round," Ferrer said. "Of course, I am not happy with my game tonight, but this is tennis."
With such a light workout during his match, Djokovic went back out to center court at Rod Laver Arena an hour later during a legends doubles match involving his friend, retired Frenchman Henri Leconte.
To much laughter from the crowd, Djokovic, dressed in a mock medical costume, pretended to give Leconte treatment at the side of the court.
Later, he was all business while talking about the final against either Federer or Murray.
"It can only do positive things to my confidence at this stage of the tournament," Djokovic said of his easy win. "I have a great feeling about myself at the moment."