They saved their biggest result for the last month of the season, but only one will earn your votes.
Was Kiki Bertens, Ashleigh Barty or Anastasija Sevastova your Breakthrough Player of the Month in October?
Have a look at the nominees and cast your vote before Thursday at 11:59 p.m. ET!
Kiki Bertens: The last woman into the WTA Finals field in Singapore, Bertens made noise in a big way by qualifying out of her group to reach the semifinals.
The Dutch No.1 went 2-1 in her round robin group, securing placement in the semifinals when US Open champion Naomi Osaka retired due to injury.
She rallied from a set down to stun Wimbledon champion Angelique Kerber in her opening match, before falling in another three-setter to Sloane Stephens in group play.
Anastasija Sevastova: Sevastova set a host of benchmarks for her career in October, beginning at the China Open in Beijing.
The Latvian reached her first Premier Mandatory final in Beijing, defeating Donna Vekić, Dominika Cibulková and Naomi Osaka before losing to Caroline Wozniacki in the final.
After this event, she reached her then-career-high ranking of World No.11, and later reached the semifinals of the Kremlin Cup in Moscow, a Premier-level event.
As the No.5 seed there, she knocked off Magdalena Rybarikova, Yulia Putintseva and Vera Zvonareva before falling to Ons Jabeur.
Ashleigh Barty: Aussie Barty won her biggest career title at the WTA Elite Trophy in Zhuhai to close out the month, as she advanced out of her round robin group before taking out defending champion Julia Goerges and Wang Qiang to raise the crown.
Who was your October Breakthrough Player of the Month? Vote now!
The winner will be announced on Friday, November 9.
How it works:
Finalists are selected by wtatennis.com
Winner is then determined by a fan vote on wtatennis.com
Previous WTA Breakthroughs of the Month for 2018
January: Hsieh Su-wei
February: Daria Kasatkina
March: Danielle Collins
April: Ana Bogdan
May: Mihaela Buzarnescu
June: Tatjana Maria
July: Wang Qiang
August: Aryna Sabalenka
September: Anett Kontaveit