A 5-1 thrashing of lowly Perth Glory at McKellar Park on Sunday booked United's spot in the finals for the first time since winning the title two years ago.

United's focus has now turned to Wednesday night's crucial encounter with Sydney FC - the first of two meetings with the ladder leader in its final three games.

United rotated its squad before a busy schedule featuring three games in the space of six days.

Teenage duo Meg McLaughlin and Grace Field both made their starting debuts and replacement goalkeeper Trudy Burke deputised for Matildas star Lydia Williams.

Lindsey said the the youngsters will come in handy as the competition gets down to the business end.

"We're getting to the latter part of the season, we've got three games in six days, so we've got to manage the fatigue,'' Lindsey said. "The girls who came in today did a great job.

''Everyone's really stepping up at the right time and we're starting to gel again.''

United's sixth win of the campaign keeps it fourth on the ladder and moves it seven points clear of fifth-placed Adelaide United, which has two games to play.

A home final is still on the cards, with United (18 points) maintaining the pressure on Sydney FC and Melbourne Victory (both 23) and Brisbane Roar (19).

United coach Elisabeth Migchelsen is keeping her team's feet on the ground after achieving their first target.

"We said as a team our aim was to reach the play-offs then it's just each game after that,'' Migchelsen said.

"I don't look at where our opponent is on the table. It's game after game.''

United deservedly took the lead in the 37th minute when defender Ellie Brush got on the end of a perfect corner from Lindsey to head the ball into the net at the near post.

It was another set piece four minutes later which stretched the advantage.

After Heyman was fouled just outside the box, Caitlin Munoz smashed the free kick with pin-point precision past the wall and into the bottom left corner.

Lindsey was rewarded for her strong game, reacting quickest to a rebound in the box to make it 3-0 in the 81st minute.

Matildas striker Kathryn Gill pegged one back for Perth in the 84th minute.

United substitute Georgia Yeoman-Dale scored twice in the space of two minutes to put the icing on the cake.

Williams, defender Sally Rojahn and attacker Ashleigh Sykes are expected to return to face Sydney FC on Wednesday night.

CANBERRA UNITED 5 (Ellie Brush 37', Caitlin Munoz 41', Lori Lindsey 81', Georgia Yeoman-Dale 90', 92') bt PERTH GLORY 1 (Kathryn Gill 84') at McKellar Park on Sunday. Crowd: 714.