Four Americans went to battle on Thursday night in Arthur Ashe Stadium, as an all-American final was guaranteed. And it was Sloane Stephens and Madison Keys who stepped up for the wins and will face each other in the US Open final on Saturday.

In a match with ebbs and flows in the first two set, Stephens played spectacular tennis in the third to defeat Williams 6-1, 0-6, 7-5.

In the first set, both big-hitters dueled from the baseline, but it was Stephens who was the first to seize an opportunity, breaking Venus to go to 3-1. Williams was haunted by an abundance of errors as she missed on many of her big, aggressive shots and she failed to settle her game down. Stephens took advantage of her tight play, broke again, and closed out the first set at 6-1 in just 24 minutes. A nervous-looking Williams gifted 17 unforced errors in the set.

In the second set, Stephens refused to make things easy for Venus in the opening game as her court movement and ball placement was superb. Williams quickly found herself in a hole but fought off 3 break points to remain on serve, as the crowd attempted to lift her out-of-sorts game. The hold appeared to fuel Venus and suddenly, Stephens lost focus as, perhaps, nerves began to play a factor. Williams quickly broke serve, consolidated the break, and refused to take her foot off the gas, sprinting to a bagel set with her high-level brand of tennis restored.

Stephens shook off the second set result fast with an opening service break to gain the advantage in the third. And after two lopsided sets, both players upped their level and compelling tennis was the result as Venus fought to break back. Stephens competed with grit to hold, but Williams would equal the set at 2-2. As the set progressed, each service game was highly contested as both players sought another pivotal service break. But it was Stephens who, behind sensational defense and steady groundstrokes, earned a break to go to 4-3 as the match intensified. Her advantage was short-lived, however, as Venus aggressively attacked with big, angled shots from both wings and evened the set with her own break.

The set turned with Venus serving at 5-5 as she pounded aggressive strikes moving Stephens around the court. But Stephens, now playing at a level seldom seen from her, seemingly got to every ball and countered with one sensational winner after another. After an incredible game of tennis, the young American broke, setting up an opportunity to serve for a spot in the final. She calmly stepped up to the occasion and closed out the match on her serve, and advanced.

Stephens found it difficult to describe the result afterward. “I have no words,” she said. “I don't know how I got here. Just hard work—that's it.” She continued, “It required a lot of fight, lot of grit. I knew if I stayed with it, hung tough, played my game, didn’t get too down on myself, I’d have my opportunity.”

In the second semifinal, Madison Keys played one of the best matches of her career, defeating CoCo Vandeweghe 6-1, 6-2.

The match featured two of the biggest hitters in the women’s game and it took little time to see it on display. But it was Keys who came out the more settled player, using her power in an effective manner. Meanwhile, Vandeweghe struggled to settle down and fell into a huge opening set hole. Keys played clean and consistent tennis with confidence and rolled to the opening set, ripping 14 winners to just 2 unforced errors in the set.

While the 15-seed cruised in her service games, Vandeweghe struggled to hold hers and Keys broke through in the second set to gain a 2-1 lead. She found success attacking the 20-seed’s second serve and struck firm, deep shots, placing CoCo on the move. Keys kept the pressure on a frustrated Vandeweghe who could not find an answer to the assault.  And despite having to take a medical timeout leading 4-1, to address a thigh issue, Keys closed out the match in fine form.

Keys confidently summed up her performance, “I think I played pretty well tonight.” The match lasted just 66 minutes which includes the medical timeout taken by Keys.

The American addressed her thigh problem, “I definitely started to feel it and was worried something more serious could happen. I felt like I needed it worked on sooner rather than later. I feel great right now, I don't think I could feel better than I do right now.”

She will have a day to address it before the championship on Saturday.