CINCINNATI, OH, USA - For the second time in as many weeks, No.16 seed Madison Keys took down the big-serving CoCo Vandeweghe to move into the second round of the Western & Southern Open.

“[CoCo and I] go from never playing each other to now playing each other back to back!” Keys laughed in her on-court interview. “That kind of sucks, but I’m glad I won.”

The two Americans met on court for the first time less than two weeks ago in the final of Stanford, where Keys edged past Vandeweghe in straight sets to claim the Bank of the West Classic title.

Vandeweghe was keen to get revenge in their Cincinnati opener - and even pushed Keys to three sets - but in the end the No.16 seed needed just under two hours to deny her and wrap up the 6-4, 3-6, 6-3 victory.

“CoCo is always going to be a tough person to have to try to get returns in,” Keys said. “She obviously raised her level in the second set, so then I had to as well in the third.

“From then it was just about who could get more balls in at the end.”

The two Americans split the first two sets in nearly identical fashion. In the first, Keys played aggressive against the booming Vandeweghe serve and grabbed an early break, dodging a break-back point and hanging on to her lead. But in the second it was Vandeweghe who got out to a fast start, breaking Keys in her first service game and keeping her out of the rallies to level the scoreboard.

Keys kept her concentration in the decider and charged ahead to a 2-0 lead - aided by two double faults from her opponent - and looked to continue the pattern set in the previous two sets.

But Vandeweghe had other ideas, roaring back a few games later and piling the pressure on the Keys serve and pulling them back even.

The Stanford champion remained undaunted, and kept her returns deep as Vandeweghe finally blinked again late in the set at 5-3, and Keys served out the match after an hour and 56 minutes.

Keys, who has never been past the second round in Cincinnati, will take on Daria Kasatkina in the next round. The American leads 2-0 in the head-to-head record against Kasatkina, with both victories coming on hard courts last year.