A-League Women premiers Melbourne City now await the Jeff Hopkins-coached Victory after they dominated play at Canberra's sold-out crowd McKellar Park on Saturday afternoon.
The Victory just scraped into the top six to play finals, but they have a strong pedigree in big games and will fancy their chances of going all the way.
Experienced attacking midfielder Rachel Lowe got the visitors on the board in the 21st minute with a poachers goal after a header by Claudia Bunge from a corner was initially saved by Canberra goalkeeper Sally James.
Lowe's back heel three minutes later was the catalyst for O'Grady to add a second. The 20-year-old Young Matildas powerhouse stormed into the box and with sheer tenacity ensured the ball ended up in the back of the net.
James did well to save a shot from Victory striker Holly Furphy, but the hosts scored at the other end on 29 minutes. Defender Sasha Grove raced onto scraps in midfield before guiding her shot expertly beyond keeper Courtney Newbon.
United should have levelled when American striker Emma Hawkins headed over the bar from point-blank range after a slick cross from veteran skipper Michelle Heyman.
Canberra had won both regular-season matches 3-1 against the Victory, but O'Grady extended the lead in the 51st minute with a powerful header from an exquisite Furphy cross.
She suffered an injury putting the ball in the net, but dusted herself off.
"I've made a reputation for myself that I am not going to back down," O'Grady told Paramount Plus post match.
"You have always got to put your body on the line, in my case anyway, so it was definitely worth it."
The Victory came into the clash with an impressive record under long-time coach Hopkins, who was at the helm for back-to-back championships in 2020-21 and 2021-22 and the 2018-19 premiership.
Canberra coach Antoni Jagarinec helmed the side to the finals last season in his first campaign in charge. He did well again to take the club, still facing a shaky future, to third in the regular season.