World number one Aryna Sabalenka had to dig deep to overcome fourth-seeded Amanda Anisimova 6-3, 3-6, 6-3 in a high-octane semi-final at the WTA Finals in Riyadh.

The Belarusian four-time major winner roared her way early on Saturday Hong Kong time to a championship showdown with Kazakhstan's Elena Rybakina, who battled past fifth-seeded Jessica Pegula 4-6, 6-4, 6-3 earlier at King Saud University Indoor Arena.

Sabalenka clocked 12 aces and saved six of nine break points to book her place in the final for a second time in five appearances at the season-ending championships.

"She always pushes me to play my best tennis," said Sabalenka, who gave Anisimova a warm embrace at the net after the match.

"Honestly, I wouldn't care if I would lose this match because we both played an incredible match and we both deserve to be in the final.

"I'm super happy to get the win. I told Amanda that she should be proud of her season, she played incredible tennis the whole season, but it's just the beginning for her. There are many good things coming her way for sure."

Both Sabalenka and Rybakina are undefeated through four matches so far this week and have a chance of earning a record US$5.235 million with a victory in the final, to be held at 12am on Sunday Hong Kong time.

Rybakina claimed a 10th consecutive win by beating Pegula to reach the championship match at the WTA Finals for the first time in three appearances.

"When I came here, I didn't have many expectations. I'm very happy the way I played in Asia but at the same time, I was quite tired," said Rybakina, who won the title in Ningbo and made the semi-finals in Tokyo to secure the final qualifying spot for Riyadh at the very last chance.

"So, for me, it was okay, last week, last push, let's see what's going to happen. And yeah, I didn't expect to go that far." (AFP)