World No. 5 Maria Sakkari fended off a second-set fight back from Aryna Sabalenka to emerge with a 6-2 6-4 victory and reach the semis of the WTA Finals for a second straight year on Wednesday, while Tunisia's Ons Jabeur overcame a sluggish start to beat Jessica Pegula.

Sakkari, 27, cruised through the first set and led 3-0 in the second before the hard-hitting Belarusian roared back, winning four straight games to take a 4-3 lead.

But the determined Greek reeled off the final three games and raised her arms in triumph when Sabalenka's running forehand landed wide on the purple indoor hard courts in Texas.

Jabeur, who fell to Sabalenka in a tight three-setter in their opening match on Monday, said the round robin format meant she had no time to sulk over the loss, as she made a spirited 1-6, 6-3, 6-3 victory over Jessica Pegula of the United States.

"I'm used to being depressed for the next two days when I lose but I didn't have much time here," the world No. 2 said after collecting her 47th win of the season.

The WTA Finals features eight women split into two sections, with the top two finishers in each group moving onto the semis.

Sakkari is the first player from her group through to the last four. Jabeur, Sabalenka and Pegula are vying for the second spot.

Pegula was surprised to discover that she was not yet mathematically eliminated, although it would take an unlikely combination of results to see her reach the semi-finals.

"I'm still in?" the world No. 3 Pegula asked at her post-match press conference. 

"That's good to know. I'm still alive, somehow."

The group featuring Iga Swiatek, Caroline Garcia, Coco Gauff and Daria Kasatkina returns to action on Thursday.

(With input from agencies)

(Cover: Maria Sakkari of Greece serves against Aryna Sabalenka of Belarus during the 2022 WTA Finals, in Fort Worth, Texas, U.S., November 2, 2022. /CFP)