Taylor Kornieck had opened the scoring for Casey Stoney's San Diego, before Portland's Raquel Rodriguez equalised.

They will face Kansas City Current in Saturday's title game in Washington DC.

"I'm still replaying the moment over and over again," said United States midfielder Dunn of her 93rd-minute strike. "It was incredible.

"Seeing the ball drop in front of the goal frame, I was like alright Crystal, here's your moment, hopefully you hit it as hard as you can and don't let anyone block the shot."

She added: "It's really hard for me to process that, five months ago, I gave birth.

"There was part of me that thought, maybe I just take the rest of this year off, maybe I hit reset and start fresh in 2023. But for me, I always wanted to end this year the best way that I could and that was working extremely hard to get back on to the pitch."

Dunn's goal came 156 days after she gave birth, with Portland head coach Rhian Wilkinson joking: "I have food in my fridge older than that."

Sunday's game marked the first time in NWSL history that two female head coaches were on the touchline in a playoff match.

The Thorns - previously crowned NWSL champions in 2013 and 2017 - are the first team in league history to reach four Championship games, having also reached the final in 2018.

Their semi-final was watched by more than 22,000 people in Providence Park, after Thorns players asked the crowd to turn up following the release of the Yates Report earlier in the month.

An independent investigation found abuse and misconduct "had become systemic" in the US top-flight. It was launched in 2021 following allegations made against North Carolina Courage's English head coach Paul Riley, who also previously coached Portland.