Madison Keys is the first American other than Serena and Venus Williams to earn a berth at the year-end WTA Finals in more than a decade.
The last American outside of a Williams at the finals was Lindsay Davenport, a former coach to Keys, in 2005.
Keys' debut in the WTA Finals, starting on Sunday, came courtesy of her winning a second career title in Birmingham, England, and reaching finals at Rome and Montreal.
She also played in the Olympic semifinals, losing to Petra Kvitova for the bronze medal.
"Being here is a huge accomplishment for me," Keys said. "I definitely want to ... prove that I've worked really hard to get here, and I'm here for a...