Zvonareva has yet to drop a set after three group matches in the event for the top eight players and ensured that she will take on No. 1 Caroline Wozniacki in one semifinal Saturday. Clijsters will face Samantha Stosur in the other.
Zvonareva, who lost to Clijsters 6-1, 6-2 in the U.S. Open final, used a strong net presence and powerful backhand to beat the Belgian for third time since Clijsters came out of retirement last year.
The first set went back and forth until Zvonareva's powerful return was netted by Clijsters. Clijsters jumped out to 3-1 in the second, but Zvonareva stormed back to tie it 5-5. She led 6-5 on a powerful backhand and raced to 40-0 on her way to winning the final game.
"It has been an amazing week so far. I had three tough matches," Zvonareva said. "They are all great players here and to win against them is nice."
Clijsters partly blamed her first loss since August on her three-set victory over Victoria Azarenka that finished in the early hours of Friday and left her exhausted.
"You know, obviously last night's match was pretty tough, and I kind of just felt it today," Clijsters said. "So obviously I'm going to have to feel much better and then just going to have to get my energy back. I kind of just felt flat out there today."
Dementieva and Schiavone were already eliminated from semifinals contention before their match, and Dementieva didn't reproduce the form she showed in beating Stosur the day before.
Schiavone's consistent returns and net play forced Dementieva into hitting returns long and wide, and the Italian was in no mood to finish her first singles appearance in the tournament without a win. At one point Schiavone won 10 of 15 games. Dementieva committed 28 unforced errors.
Schiavone was happy to be heading to the Fed Cup final between Italy and the United States in San Diego next week with a win.
"I played a little bit better and was little bit more focused and confident than Elena," she said.
Dementieva ended her 12-year career, featuring 16 singles titles, two Grand Slam singles finals and the Beijing Olympics gold medal, with an emotional on-court ceremony surrounded by her rivals. She said she had no regrets.
"It is so emotional. It is so hard to say goodbye. I am going to miss you so much," Dementieva said.
The 29-year-old Russian compiled a 576-273 record and a place in the year-end top 10 for the seventh time in eight years.
In the final match of the night, Azarenka of Belarus earned her first victory of the tournament with a 6-4, 6-1 victory over ailing Jelena Jankovic of Serbia. The No. 8-ranked Jankovic didn't win a match all week, often being outplayed and looking sluggish especially in the sets of her matches.
She hit seven double-faults Friday and won only one of eight break points.
"It was a tough match. I am happy that I finished the season with a win," Azarenka said.
Jankovic has suffered through a number of injuries this year, including ankle, back and sinus problems.