WHAT HAPPENED: In a tight battle of big serves, deep ground strokes and changing fortunes, between two lanky and long-limbed power hitters, 10th-seeded Karolina Pliskova came from behind and advanced to her first major quarterfinal, defeating Venus Williams, the two-time champion, in a third-set tiebreak.

Pliskova outlasted Williams, 4-6, 6-4, 7-6. The tall Czech, 24, showed nerves early, beginning the match looking very tight in her first appearance in Arthur Ashe Stadium – but not late.

Pliskova rebounded from squandering three match points on her serve at 6-5, finally taking the victory on her fifth opportunity.

"It was very difficult when I lost my serve at 6-5," Pliskova admitted. "But I am very happy to come back to win."

Pliskova entered the Open on a hot streak. In Cincinnati, she thumped Angelique Kerber of Germany, the second-ranked player in the world, preventing her from taking over the top spot from Venus’s sister Serena.

In the 67-minute final set, Pliskova held a 4-2 advantage, but Venus clawed back, striking deep, angled balls to even it up at 4-all. The Czech broke serve for the second time in the set at 5-5, when her forehand drive clipped the tape and floated over Williams’s outstretched racquet for a winner.

Serving for the match, Pliskova quickly grabbed a 40-0 lead. But Williams again dug in, erasing three match points and claiming the break to get to a deciding tiebreak.

The tiebreak was all Pliskova.

In the opening set, Williams stormed to a 5-1 lead, repeatedly closing points at the net and making the tall Czech look distinctly average – often she was caught flat-footed watching the ball sail by. Pliskova finally began to find her rhythm. In the second set, she began putting more big serves in play (winning 89 percent of her first-serve points).

"Obviously, my serve is my biggest weapon," said Pliskova.

WHAT IT MEANS: Pliskova, who has been as high as No. 7 in the world, possesses effortless power in her smooth, flat ground strokes, and she is the tour leader in aces. Yet until this match she was considered an underachiever at majors; she was previously the only player in the Top 20 not to have reached a Slam quarterfinal.

Williams, at 36 the oldest woman in the draw, reached the quarterfinal in Flushing Meadows in 2015 (losing to her sister Serena) after a five-year drought here, in which she didn’t advance beyond the third round.

A tight match between Williams and Pliskova was not unexpected. They had met just once before, in 2015, and though Venus won in straight sets, it was an exceedingly close match: 7-5, 7-6.

THE QUESTION: This is the farthest Pliskova has made it in a major; can she keep it going and reach her first semifinal?