The Greek was the first alternate to replace any player who would pull out from the season finale, having finished ninth in the WTA Race, behind Muchova. The 27-year-old Muchova along with fellow Czech Marketa Vondrousova were all set to make their debuts at the event.
But Vondrousova will be the one heading there alone after her countrywoman withdrew due to a persistent wrist injury. On Tuesday, Muchova shared the disappointing news, that despite taking extra precautionary measures with doctors, the injury did not heal in time.
Since her last appearance at the US Open (where she fell to a straight sets defeat to eventual champion Coco Gauff in the semifinal), Muchova spent nearly two months on the sidelines. She sacrificed the entire Asian swing in order to recuperate. But the injury requires a longer treatment period and will therefore miss out on the eight-woman party in Cancun.
Muchova's miss is Sakkari's gain. The Athenian will get another chance to renew her love affair with Mexico, a country which she called a "second home" following her title success in Guadalajara towards the end of September.
"Not the way I wanted to qualify, but I'm super excited to be coming back to Mexico!"
Sakkari won her first WTA 1000 and just her second career title in western Mexico, beating first-time finalist Caroline Dolehide in a tournament deficient of top-drawer names last month. Despite a lower winning rate in comparison to the past two seasons, this has been Sakkari's best year on tour.
The 28-year-old has reached the semifinals or better in eight WTA tournaments this year, and she could realistically surpass last year's total match wins of 40 (currently 38). Historically, the WTA Finals have produced some surprise champions in the past decade, most notably, Dominika Cibulkova, Garbine Muguruza, and Caroline Garcia. And Sakkari could be the dangerous floater in the draw.