The eighth-seeded Seles showed flashes against her fellow American of the player that dominated the 1990s along with Steffi Graf. She stopped Williams' 22-match winning streak in reaching her first major semifinal since the 1999 French Open.
Seles has won the Australian Open four times, capturing the last of her nine Grand Slams here in 1996.
She will face third seed Martina Hingis of Switzerland in the semifinals. Hingis handed Seles her first defeat in 34 matches at Melbourne Park in 1997, going on to win the first of three
straight crowns here.
Hingis posted a 6-2, 6-3 victory over unseeded Italian Adriana Serra Zanetti Tuesday to advance to her sixth straight Australian Open semifinal.
Johansson will take on No. 26 Jiri Novak of the Czech Republic, who routed unseeded Austrian Stefan Koubek, 6-2, 6-3, 6-2, to reach his first major semifinal.
All four matches were played under the retractable roof of Rod Laver Arena due to rain.
Williams, who had her right thigh heavily taped, won the first set in 50 minutes but suffered a hamstring injury.
"I really started feeling it around 4-3," said Williams, who called for the trainer at 4-4. "I really don't know when I did it or what happened. It was really strange because I've had pain in areas before where I've been hurting but never where it just sort of came up on me so quickly, where I've never had pain in that area before."
Seles, herself bothered by a sore throat, started to rally right away, opening the second set with a break of serve. She broke again before evening the match by winning the set in just 32 minutes.
The former world No. 1 took advantage of two of Williams' 49 unforced errors to break serve in the fifth game of the deciding set. She withstood a challenge while leading 4-3, but broke again in the final game to defeat Williams for the first time in seven meetings.
"It was such a see-saw match and to pull through it and to stay really focused at the end was really good," Seles said."One or two service games really helped me out there and I was pretty
lucky to end up winning from being 0-40 down."
Seles believes she will be physically fine for her meeting with Hingis. She is just 4-13 lifetime against her Swiss foe, but has won the last two encounters.
Williams, the reigning Wimbledon and U.S. Open champion, endured her first loss since a quarterfinal setback to Meghann Shaughnessy in the quarterfinals of the Benk of the West Classic
last July. But, she did not blame her loss on injuries.
"I think she played well and she capitalized on all her opportunities, whereas I didn't always, Williams said. "That was the story of the match."