After plenty of progress to be satisfied with last season, did these two contenders reach their performance ceiling for the time being?

"Adjusting my attitude has definitely led to gradual improvement," the two-time major semifinalist wrote for Eurosport.

What all great matches are about: human emotions. This anxious epic in Paris was far from perfect, but it was tennis at its hair-raising best.

The Estonian improved to 7-0 in semifinals this year with a 6-1, 3-6, 6-3 victory over the Greek in Guadalajara.

The last time Sakkari lost to a Top 5 player was 22 months ago, when Naomi Osaka beat her in Brisbane.

The semifinal match-ups are now set in Guadalajara: Sakkari will square off against Anett Kontaveit, while Garbine Muguruza will take on Paula Badosa.

Monday's matches also feature five-time ATP Finals champ Novak Djokovic and WTA Finals top seed Aryna Sabalenka.

The Indian Wells champion will advance to the semifinals if Aryna Sabalenka wins a set against Iga Swiatek tonight.

Depending on the outcome of Saturday's matches in Guadalajara, one player could clinch Group Chichén Itzá while one competitor will be eliminated from the season finale.

The Greek gave Iga Swiatek an emotional hug following their match in Guadalajara.