Both women had their chances to put the match away in the 68-minute-long third set but it was the World No.1 who prevailed victorious to reach the finals.
Former No. 1-ranked Wozniacki is potentially one win away from a breakthrough Grand Slam title after advancing 6-3, 7-6 (2) over Elise Mertens on Thursday.
The fifth-seeded Indo-Hungarian pair took one hour and 15 minutes to get the better of Cabal-Spears duo 6-4 7-6 (5) in the quarterfinal duel.
The 36-year-old Federer also became the oldest man to reach the semifinals at Melbourne Park since Ken Rosewall did it in 1977 at the age of 42.
Halep, a two-time French Open finalist, is aiming for another shot at a first Grand Slam title after quickly overcoming a slow start to beat sixth-seeded Karolina Pliskova 6-3 6-2 in the quarterfinals.
The No. 58-ranked Chung is the first Korean player to reach the last four of a major, and the lowest-ranked man to reach the Australian Open semifinals since Marat Safin in 2004.
The defending Australian Open champion Angelina Kerber will clash with WTA No.1 Simona Halep in the semifinals which promises to be an absolute treat.
Wozniacki, who can return to the No. 1 ranking with her first Grand Slam singles title, plays Elise Mertens in the semifinals.
Cilic will play a semifinal against No. 49-ranked Kyle Edmund, who earlier beat number three seed Grigor Dimitrov in four sets on Tuesday.
The Indo-Hungarian pair will now face the unseeded duo of Juan Sebastian Cabal from Colombia and Abigail Spears from the USA in the quarterfinals on Wednesday.
The 23-year old Brit checked all those boxes on Rod Laver Arena, setting himself up for a match against either top-ranked Rafael Nadal or No. 6 Marin Cilic for a spot in the final of the season's first Grand Slam.
Edmund will play either top-seeded Rafael Nadal or No. 6 Marin Cilic in the first men's semifinal on Thursday.
The 58th-ranked Chung relentlessly attacked Djokovic - who is playing his first tournament since Wimbledon because of an injured right elbow - in the 7-6 (4), 7-5, 7-6 (3) fourth-round win.
The 26-year-old American, who entered the season's opening major ranked 97th, missed a match point in the fourth set but held on for a 6-2, 4-6, 7-6 (4), 6-7 (7), 6-3 win over fifth-seed Thiem.
Halep, who could lose her No. 1 ranking if she doesn't win the title here, extended her record of not having lost a fourth-round match on hard courts at a Grand Slam since the 2013 U.S. Open.
Combining with Edouard Roger-Vasselin of France, Bopanna lost to Oliver Marach of Austria and Croatia's Mate Pavic 6-4, 7-6 (7-5), 3-6 at the Melbourne Park.
Tomas Berdych, who beat Fabio Fognini in straight sets earlier Monday, will be Federer's quarterfinal opponent.
The U.S. Open finalist is yet to drop a set at Melbourne Park and is averaging a brisk 62.5 minutes on court through her first four rounds.
The Johannesburg-born Edmund is the first British man other than Murray to reach the quarterfinals in Melbourne since John Lloyd was beaten in the quarters in 1985.
The Indo-Hungarian pair brushed aside the duo of Ellen Perez and Andrew Whittington 6-2, 6-4 on the Margaret Court Arena.
Top News
Latest News
