Jessica Pegula (3-0) vs. Coco Gauff (2-1)

“We know each other’s game’s so well,” Pegula said the last time she faced off against her doubles partner, in Montreal this summer. “So we kind of know what we’re going to do to each other, know what our goal is.

“It’s just kind of trying to execute it at the right times.”

This will be the 2023 tiebreaker between Pegula and Gauff. They’ve played twice, and each has won once: Gauff in straight sets on grass in Eastbourne; Pegula in three sets on hard courts in Canada. It’s fitting that the rubber match comes in the semis of the WTA Finals. While they’re 10 years apart in age, the two Americans have each had career-best seasons, and joined each other in the Top 5 for the first time.