If she wins, the 37-year-old will nab her 24th Grand Slam singles title, tying the legendary Margaret Smith Court, the current record holder. The victory would also give Williams the most U.S. Open singles titles (seven) and most U.S. Open match victories at Flushing Meadows (101).
She would also join a list of three other female tennis icons -- Margaret Court, Evonne Goolagong, and Kim Clijsters -- who won a Grand Slam singles title after becoming a mother.
“It’s cool that I’ve been in more finals than anyone on tour after being pregnant. That’s kind of awesome,” Williams said ahead of the match. “It’s not easy to go through what I did and come back — and so fast. To keep playing, to also not be 20 years old — yeah, I’m pretty proud of myself.”
Williams, who is ranked eighth in the world, has looked strong the past two matches, defeating Qiang Wang in the quarterfinals before taking out Elina Svitloina 6-3, 6-1 in the semifinals. In fact, she's only dropped one set in the entire tournament -- against up-and-coming American Caty McNally in the second round.
The tennis superstar is also attempting to win the U.S. Open a year after losing to Naomi Osaka in last year's finals, a game that had its share of penalties and controversy.
When she was asked about last year's final, Williams said: "It hasn't really crossed my mind."
At 19, Andreescu is 18 years younger than Williams and wasn't even born when the American won her first Grand Slam in 1999 at the U.S. Open. This will be the biggest age gap in a women’s Grand Slam singles final in the Open era, which began in 1968.
The 15th-ranked Canadian is playing in her fourth Grand Slam but had never made it past the second round at the U.S. Open. She's only lost two sets this tournament and won her previous matchup against Williams, who retired with a back injury in last month's Rogers Cup.
"It feels pretty good because you never know what can happen in a match. I'm trying not to take anything for granted right now. I'm just going to keep doing what I'm doing," said Andreescu.
Andreescu has won 12 consecutive matches on summer hardcourts and hasn't lost a completed match since March.
“It’s just surreal. I really don’t know what to say,” said Andreescu after defeating Belinda Bencic in the semifinals on Thursday. “It’s a dream come true playing against Serena in the final of the U.S. Open. Hopefully, I can just keep the momentum going for the final.”
Williams praised her opponent ahead of the match.
“She’s a great player,” she said. “She mixes things up. You never know what is going to come from her. She serves well, moves well, has a ton of power. She’s very exciting to watch. It’s good. I think it’s great for women’s tennis.”
The Associated Press contributed to this report.