The duo were integral to United's formidable defence when they went through the season undefeated to win the W-League last season, conceding just 11 goals in 12 games.

But Canberra has conceded seven goals in its past two W-League games, leaving Brush and Cooper particularly motivated for their milestone game.

''It's good it's Caitlin and I, both our 50ths, and our main aim will be to keep a clean sheet, and work together,'' Brush said.

''It will be good to play it [the 50th game] in front of the home crowd, [but] it won't mean much though if we aren't able to get a result.''

Brush has served as United's captain or co-captain for all her 50 caps, missing just three games, including the 3-0 loss to Melbourne two weeks ago through suspension.

''There has been quite a few reshuffles with some players coming in, but definitely we're working hard as a defensive unit'' she said.

''It's just some scrappy goals and little mistakes we're making that have been causing some of those goals; [we're] just really hoping to iron out some of those mishaps.''

Improved defence has been Canberra's focus as it prepares for Perth, a team that has scored 12 goals in its past three games, and boasts the firepower of Matildas strikers Lisa De Vanna and Kate Gill.

Brush and Cooper, who played her first 20 caps as captain of the now-defunct Central Coast Mariners, will be charged with containing de Vanna and Gill in a game that could make or break their season.

''We need to win this game,'' Cooper said. ''We're a bit down at the moment, but I think we can pick ourselves up and go forward.

''Ellie and myself really just need to stay focused and not let anyone pass us.

''It's going to be a challenge, but we're up for a challenge.''

WEDNESDAY

W-League: Canberra United v Perth Glory, at Deakin Stadium, 6pm.