Svetlana Kuznetsova will seal the last place in the WTA Finals if she defeats Daria Gavrilova on Saturday after beating Elina Svitolina to reach another Kremlin Cup final.
Defending champion Kuznetsova headed to Moscow knowing a second WTA title of the year would guarantee her a return to the season-ending tournament in Singapore, which starts on Sunday, at the expense of Johanna Konta.
The top seed will board the plane to south-east Asia if she gets the better of Gavrilova in her homeland after battling past Svitolina 6-1 6-7 (2-7) 6-4 on Friday.
Kuznetsova, given a wildcard entry to the event in her homeland, raised her game in the deciding set to end the challenge of the fourth seed from Ukraine on Friday.
Both players had 10 break point opportunities, but world number 15 Svitolina could only grasp two of them and failed to hold six times to lose at the semi-final stage for the third time her last four tournaments.
Unforced errors from Kuznetsova and some classy Svitolina ground strokes enabled the fourth seed to take a second-set tie-break, but the Russian recovered and is just one win away from another appearance in the season-ending WTA Finals.
There could yet be a sting delivered by the unseeded Gavrilova, though, after the Australian sent Julia Goerges packing with a 7-5 6-1 victory in the second semi-final.