Western United are set to play finals in their inaugural A-League season after beating Perth Glory 2-0 at Bankwest Stadium.

Besart Berisha opened the scoring in the 27th minute then secured his brace from the penalty spot in the 52nd.

The win puts Western into sixth - level with Adelaide United on 36 points but with a vastly superior goal difference (+10 to -5).

Adelaide have played all their 26 games while Western have two games to come.

"We didn't want to wait until the last or second last game to qualify and make finals football, so we put all our eggs in the basket tonight and the boys did extremely well," Western coach Mark Rudan said.

"We won the game and we're in there right now and it's important that we don't take the foot off it but we'll enjoy it that's for sure and we'll give some players a good rest."

United reaped the rewards of a clever set piece in the 27th minute.

Diamanti took a corner short to Max Burgess, who curled a delightful ball towards the back post.

Perth goalkeeper Liam Reddy came off his line and punched the ball, only for it to ricochet off Berisha's chest and into the goal.

United doubled their lead early in the second half when Connor Pain won a penalty.

Perth's Ivan Franjic went to ground and caught the wing-back with his sweeping leg, with referee Chris Beath pointing to the spot.

Berisha coolly slotted the penalty for his 18th goal of the season - two behind golden boot leader Jamie Maclaren.

Western's night was soured when Josh Risdon hurt his knee in the first half and was substituted in the 61st minute - though Rudan said it was just a "clash of two knees".

In the 64th minute, Kilkenny's long-range strike forced a save from Filip Kurto, while the United goalkeeper also claimed Fornaroli's 77th-minute free kick.

It saw Perth, who were already locked in to play finals, slipping to their fourth loss in six games since the season restart.

"Of course we wanted the result, I'm not going to deny that. But the performance was much improved," Perth coach Tony Popovic said.

"We got some more minutes into some players legs, which which was important - players that haven't had a lot of minutes throughout the year got another 90 minutes.

"So, in 10 days time. I'm sure we will definitely be ready for whoever we play."