Toronto teen in US Open semis

Bianca Andreescu, a winner this year at Indian Wells and Toronto, is the first teen in the US Open’s last four since Caroline Wozniacki in 2009. #USOpen #BiancaAndreescu

Bianca Andreescu of Canada celebrates after winning her Women's Singles quarterfinal match against Elise Mertens of Belgium on day 10 of the 2019 US Open at the USTA Billie Jean King National Tennis Center on 4 September 2019 in the Queens borough of New York City. (Elsa/Getty Images/AFP)

NEW YORK — Canadian Bianca Andreescu became the first teen US Open semifinalist in a decade, rallying to defeat Belgium’s Elise Mertens on Wednesday and advance to a last-four matchup with Belinda Bencic.

Andreescu, a 19-year-old from suburban Toronto, downed 25th seed Mertens 3-6, 6-2, 6-3 to book a Thursday clash against fellow Slam semi-final debutante Bencic, the Swiss 13th seed who beat Croatian 23rd seed Donna Vekic 7-6 (7/5), 6-3.

“I’m honestly speechless,” Andreescu said. “I need someone to pinch me right now. Is this real life?”

Serena Williams, seeking her 24th Grand Slam singles title to match Margaret Court’s all-time record, faces Ukraine’s fifth-seeded Elina Svitolina in Thursday’s other semi.

Either Bencic or Andreescu, who have never played each other, will reach her first Slam final on Saturday at Arthur Ashe Stadium, where first-time Slam winners have been crowned three of the past four years.

“Semifinal feels great right now,” Bencic said. “I was dreaming about this day coming but you never know. I worked hard for this. Yeah, very nice feeling.”

Andreescu, a winner this year at Indian Wells and Toronto, is the first teen in the US Open’s last four since Caroline Wozniacki in 2009.

She credited being tested in her wins with giving her the poise to battle back after dropping the first set against a foe who had not dropped a set in the tournament.

“I think it’s just the experience from playing these huge events this past year,” she said. “All that experience is just catching up.”

Andreescu could become the first teen to win a Grand Slam title since Maria Sharapova captured the 2006 US Open and she would be the youngest US Open champion since Russia’s Svetlana Kuznetsova in 2004.

“This is honestly so crazy,” said 15th seed Andreescu. “A year ago I was in the qualifying round. I remember I was suffering from a back injury.”

Mertens had lost only 16 games in four matches, but Andreescu, her first seeded foe, hit 40 winners to 22 for Mertens.

Mertens broke for a 3-1 edge when Andreescu missed a backhand volley then held twice to claim the first set in 38 minutes.

“I was getting irritated because I wasn’t playing my best tennis,” said Andreescu.

Andreescu broke at love for a 4-2 lead and closed the second set by taking 16 of the last 20 points.

In the third, Andreescu smashed a backhand winner to break for a 5-3 lead and another on match point.