Lauren Davis hits a backhand during her 6-2, 6-3 win over Jessica Pegula in a Citi Open semifinal between two 22-year-old Americans on Saturday night. (Chris Kleponis/Agence France-Presse via Getty Images)

Lauren Davis didn’t need to do anything fancy Saturday night.

She hit her serves, returned her shots without much flair, moved the ball from sideline to sideline, and wore out Jessica Pegula, whom she was facing for the first time. All Davis had to do was hit it over the net and wait for a mistake. And waiting on the mistakes worked as Davis won the all-American semifinal match, 6-2, 6-3, at the Citi Open.

Davis advanced to the final against Yanina Wickmayer, who outlasted Yulia Putintseva earlier in the day.

For Davis, 22, this was not a position she anticipated being in heading into the tournament.

“Not at all,” said Davis, who moves on to her first WTA final. “I was confident because I put the work in, but this is definitely beyond what I expected.”

Jessica Pegula gets ready for a return against Lauren Davis. Pegula is ranked 173rd in the WTA, and Davis is 122nd. (Grant Halverson/Getty Images)

Pegula, also 22, made a bit of a run in the second set, rallying from being down 3-1 to tie the score. But with a mental switch flipped and some sloppy points from Pegula during deuce of the seventh game, Davis pulled ahead and never looked back.

“I relaxed a little bit, and she stepped up her level and I stayed the same,” Davis said. “I think the sense of urgency just really started kicking in at 3-all. I think I ended up raising my level then and got lucky.”

Despite a lack of experience of deep runs in tournaments, Davis will be ready if Saturday’s performance is any indication.

“I’m really excited,” said the 122nd-ranked Davis. “I’ve worked hard, so I’m just really happy that my hard work is paying off. It’s really a great feeling, and I’m really looking forward to tomorrow.”

Earlier in the day, as fans braving the heat took refuge under the minimal shade at Rock Creek Park Tennis Center’s stadium court, Wickmayer and Putintseva squared off in their semifinal match under the blazing sun on a surface that reached nearly 140 degrees.

The 44th-ranked Wickmayer, of Belgium, outlasted No. 45 Putintseva in straight sets, 6-4, 6-2 . Wickmayer advanced to her 11th career WTA final.

“Playing finals is everything we want,” Wickmayer said. “That’s why we work hard. That’s why we go out and practice day in, day out, just to be on the big stage playing those finals. It’s great playing another one.”

Yanina Wickmayer of Belgium plays a forehand against Yulia Putintseva of Kazakhstan in the other Citi Open women’s semifinal. Wickmayer won, 6-4, 6-2, and will play in her 11th WTA final. (Chris Kleponis/Agence France-Presse via Getty Images)

The heat was no doubt a factor in the match. Doused in sweat, Wickmayer and Putintseva were reluctant to chase down any shot that would have required a sprint.

Putintseva, from Kazakhstan, didn’t show nearly as much fire as in her typical matches, though she did lash out at her coach during the last changeover. And Wickmayer didn’t appear to have the energy to celebrate after she won.

“Here we lose a lot of fluids, a lot of sugars, so it’s not easy sometimes to stay full of energy,” Wickmayer said. “I think that’s the toughest part.”

The two had faced each other just once before, in 2013 in Birmingham, England, where Wickmayer defeated the then-teenage Putintseva on a grass court.