No.6 seeds Nicole Melichar-Martinez and Ellen Perez moved into the semifinals of the WTA Finals Riyadh presented by PIF on Wednesday. Their cause was boosted by their 6-1, 6-3 defeat of No.1 seeds Lyudmyla Kichenok and Jelena Ostapenko on the last day of Green Group action.

WTA Finals Riyadh: Scores | Schedule | Standings

Last year's WTA Finals runners-up, Melichar-Martinez and Perez finished the round-robin stage with a 2-1 record.

Later in the day, Melichar-Martinez and Perez's path to the semis was completed when No.8 seeds Katerina Siniakova and Taylor Townsend squeaked past No.3 seeds Hsieh Su-Wei and Elise Mertens 3-6, 6-3, [10-8] in the final Green Group match on Wednesday evening.

Reigning Wimbledon champions Siniakova and Townsend had already qualified for the semifinals on Monday, and they emerged as the undefeated Green Group winners with their comeback win over reigning Australian Open champions Hsieh and Mertens.

If Hsieh and Mertens had held on for that victory, they would have won the Green Group, pushed Siniakova and Townsend into second place, and eliminated Melichar-Martinez and Perez. Instead, Hsieh and Mertens' week ends in the group stages.

Green Group - final standings - 3x2

Melichar-Martinez, Perez power through: Wednesday's first result leveled those teams' head-to-head at two wins apiece. Kichenok and Ostapenko notched a pair of straight-sets wins in 2022, but Melichar-Martinez and Perez have now taken both of their 2024 encounters (following their victory in the Indian Wells quarterfinals).

Kichenok and Ostapenko got off to a disastrous start, dropping serve courtesy of two Kichenok volley misses and consecutive Ostapenko double faults. That set the tone for a first set in which the Ukrainian-Latvian pair's unforced errors accounted for 18 out of the 26 points won by Melichar-Martinez and Perez.

The second set was slightly more competitive, but once Melichar-Martinez and Perez broke Kichenok's serve for 2-1, the American-Australian duo were able to maintain that lead to the finishing line, wrapping up the victory in just 59 minutes. Kichenok and Ostapenko finished with 34 unforced errors outweighing their 13 winners, while Melichar-Martinez and Perez tallied eight winners and 12 unforced errors.

"Our first couple of matches, the first one was topsy-turvy and the second was meh," said Melichar-Martinez afterwards. "Today we really focused, and if it's our last match here, at least we end on a high."

Perez added that their tactics and team spirit had been spot on.

"We made a lot of first serves and were able to jam them up pretty well," she said. "We kept really positive and energetic, and that was the goal for the match -- just to stay upbeat."

US Open champions Kichenok and Ostapenko finish their second WTA Finals appearance with a 0-3 round-robin record, having held match point over Siniakova and Townsend in their opening contest.

Siniakova/Townsend finish WTA Finals group stage undefeated

Siniakova/Townsend hold on to top spot: Siniakova and Townsend finished the group stage with a 3-0 record, but it was not without its difficulties. They had to save a match point before outlasting Kichenok and Ostapenko in their first match of the event.

Then, on Wednesday night, Siniakova and Townsend needed to overcome the loss of the first set, barreling through the second set to reach the match-tiebreak.

Siniakova and Townsend led 8-2 in the breaker, but Hsieh and Mertens pulled it all the way back to 8-7 before Siniakova and Townsend could clinch victory after 1 hour and 26 minutes.