'Easier physically' 

A day after saving two match points to beat Jelena Ostapenko, second seeded Jessica Pegula had a much easier time, cruising to a 6-3, 6-2 win over Beatriz Haddad Maia.

Pegula won six matches to reach the final four in Doha two years ago after coming through the qualifiers.

"It's a little bit different than the qualifying days," she said.

"It's a lot easier physically, but definitely still very tough with how strong and tough the field is."

Pegula hit 22 winners to 16 unforced errors on Thursday while Haddad Maia made just 12 winners to 20 unforced errors.

The American will face Maria Sakkari after the Greek knocked out WTA Finals champion Caroline Garcia of France 6-2, 6-7 (5/7), 7-6 (7/5).

"The conditions were very tough for both of us," Sakkari said.

"I think we did a really good job in the second set of holding our serves and not giving the opponent a chance to break. You don't see that often in women's tennis. It was pretty impressive."

Sakkari finished with 30 winners to 21 unforced errors while Garcia finished with 43 winners to 44 unforced errors.