WHAT HAPPENED: Madison Keys did not disappoint.

The No. 15 seed became the final piece of an all-American puzzle on Wednesday night at the USTA Billie Jean King National Tennis Center, joining three other Americans in the US Open semifinals. The Californian strolled confidently past Kaia Kanepi of Estonia, 6-3, 6-3.

Keys blasted eight aces in crushing Kanepi.

Four Americans in the semifinals is "pretty awesome," said Keys.

The encounter between Keys and Kanepi would seem to be a mismatch, given that the American was seeking her second career major semifinal against a qualifier ranked a lowly No. 418. That, however, is not Kanepi's natural place in the tennis order: the powerful 32-year-old was ranked as high as No. 15 in the world in 2012 and has been to a Grand Slam semifinal six different times in her professional career.

The Estonian has recently been slowed by a slew of injuries and health setbacks to her feet, battling plantar fasciitis issues in 2016.

 

play video Keys vs. Kanepi

Kanepi plays a similar game to Keys, but the American possesses much bigger weapons with her serve and forehand. Perhaps the biggest question coming into the quaterfinal was how the 22-year-old Keys would handle the pressure trying to become the fourth American semifinalist.

"I was really nervous all day," Keys admitted.

Right out of the gate, though, Keys demonstrated that she would not be beset by nerves. She struck two aces and two service winners to take the opening game at love and set the tone for the match.

Kanepi played Keys tighter in the second set, but the challenger proved unable to play the role of spoiler. On her second match point, Keys claimed her place in the semi.

WHAT IT MEANS: Not since 1985 have all four women's semifinalists at a major been Americans. And at the Open, four Americans haven't gone this deep since 1981.

Keys is through to her second major semifinal, after reaching the last four at the Australian Open in 2015, her previous best result at a major. Keys is having a fine year, returning to play after two surgeries on her left wrist at the end of 2016.

MATCH POINT: Keys advances to face her compatriot CoCo Vandeweghe. Keys has beaten CoCo in on two occasions, both of which came this summer on hard courts at the Western & Southern Open in Cincinnati and the final of the Bank of the West Classic in Stanford.

Match stats