Aryna Sabalenka won twice on Friday at the WTA Finals in Fort Worth, Texas.
First, the seventh-seeded Belarusian player beat third-seeded Jessica Pegula of the United States 6-3, 7-5 in her final round-robin match in the Nancy Richey Group.
Then when fifth-seeded Maria Sakkari of Greece won the first set against second-seeded Ons Jabeur of Tunisia in the finale of the Nancy Richey Group, Sabalenka sealed the group's second playoff-qualifying spot.
Sakkari, who had previously clinched first place in the group, went on to beat Jabeur 6-2, 6-3.
Sakkari wound up 3-0 in round-robin action. Sabalenka went 2-1, Jabeur 1-2 and Pegula 0-3.
The season's eight top players were divided into the Nancy Richey Group and the Tracy Austin Group for round-robin play. The winner of each group will play the runner-up from the opposite group in the semifinals Sunday, with the victor in those two matches heading to the final on Monday.
The prize pool is $5 million, and an unbeaten champion would earn $1.68 million.
Sabalenka prevailed thanks to compiling more winners (19-12) and fewer unforced errors (26-18) than Pegula. Sabalenka also won 80 percent of her first-serve points.
"I definitely was happy with my serve -- for the (first) half of the match," Sabalenka said. "I'm just happy that I was really focused from the beginning to the end and I was able to finish this match in two sets."
Jabeur was done in by unforced errors: 31 to Sakkari's 10. Both players finished with 11 winners.
The Tracy Austin Group concludes on Saturday, with sixth-seeded Caroline Garcia of France facing off against eighth-seeded Daria Kasatkina of Russia in a battle for second place. Both players are 1-1, so the winner on Saturday will make the semifinals while the loser will be eliminated.
The other Saturday match has little significance. Top-seeded Iga Swiatek of Poland, who already wrapped up first place at 2-0, will oppose fourth-seeded Coco Gauff of the United States, who is eliminated at 0-2.
WTA Finals group standings
Nancy Richey Group
1. Maria Sakkari, 3-0
2. Aryna Sabalenka, 2-1
3. Ons Jabeur, 1-2
4. Jessica Pegula, 0-3
Tracy Austin Group
T1. Iga Swiatek, 2-0
T1. Caroline Garcia, 1-1
T3. Daria Kasatkina, 1-1
T3. Coco Gauff, 0-2
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