In hot and humid conditions at Clipsal Stadium, Glory dominated the opening half in this second versus third encounter, going ahead through Trifiro's close-range strike in the 23rd minute.

"I think it was a tough game, we lost our way a little in the second half bit but it's probably a natural transition when you are one nil up in a semi final," coach Gareth Naven said "Congratulations to the players but obviously we've got another step to take next week

"At the end of the day everyone wants to win things and we have the benefit where winning and development are tied in the same link at this age so I think the boys will look forward to next weeks game."

Tommy Amphlett looked particularly dangerous as he took on Adelaide's defence time and again before half-time, but after the break, it proved a different story as Adelaide upped the intensity against a young Glory side that had run itself ragged.

The Reds may have dominated the possession, but striker Francesco Monterosso missed some good chances to level and Glory hung on to take their place in next week's decider against Gold Coast United, which beat Central Coast earlier in the day.

Despite the conditions, the match started at a furious tempo, although it was Glory that immediately took control of play through a dominant midfield led by Trifiro and Hayden Doyle.

In the ninth minute a clever ball from Doyle released Amphlett down the right, the forward's cross being headed at goal by Mario Marcinko, whose effort was tipped over the bar by impressive Adelaide goalkeeper Mark Birighitti.

Amphlett was proving a nightmare for Adelaide leftback Perry Mitris, the sometime seniors' striker showing off his full range of tricks as he set up two chances for Marcinko over the next 10 minutes, Marcinko twice being denied by brave Birighitti dives.

But Glory looked a good thing to score and the goal finally came in the 23rd minute as Joshua Risdon crossed from the right.

Birighitti couldn't grasp the cross cleanly under pressure from Marcinko and the ball fell at Trifiro's feet, the midfielder making no mistake from close-range as he put his side ahead.

Perth almost doubled their advantage a minute later as a deflected Adelaide defensive clearance released Amphlett through on goal, but Birighitti bravely smothered the ball at the striker's feet.

Adelaide enjoyed their best spell of the period before the half-hour mark as Monterosso and Insheob Shin sent efforts wide of the upright.

In the 31st minute, a long ball from Birighitti picked out Monterosso 15 metres from goal, but the striker's snap shot was sent over the bar by a fingertip save from Glory stopper Alex Pearson, who also tipped over Monterosso's header a minute later from the resultant corner.

Adelaide's reliance on long balls from the 'keeper however, was seeing the visitors appear somewhat one dimensional with Glory's defence sitting deeply and picking these off with relative ease.

Perth on the other hand, were running the ball through the midfield and looking to Amphlett to send in the dangerous crosses from the right, although his fine work was often sent over the bar by rushed attempts as Adelaide got numbers back.

However the introductions of Michael Doyle and Liam Wooding for Andrew Ciarla and Shin at half-time, along with some structural adjustments, reinvigorated the Reds, who appeared a totally different outfit after the break.

In the 51st minute a mis-placed pass from Glory skipper Steven Hesketh put fellow defender Sam Mitchinson under pressure as Joseph Wright stole possession and raced towards goal only to be denied by Pearson at the near post.

Five minutes later Monterosso saw his header at goal cleared off the line by Risdon as Adelaide continued to pile up the pressure.

An unmarked Monterosso mistimed his jump in the 64th minute, sending a free header over the bar from Wooding's cross, while Evan Kostopoulos fired wide just a minute later.

As the match moved into its last 20 minutes, Glory skipper Hesketh proved immense with the central defender hurling his body into several challenges that repelled one Adelaide attack after another.

There was still time for Monterosso to send another header over the bar during injury time, but Glory's efforts bore fruit and the club now heads to Melbourne for next week's decider, which will be the pre-game clash ahead of the Hyundai A-League final between Victory and Sydney FC,

Perth Glory 1    (Trifiro 23)

Adelaide United:  0