Former Socceroos midfielder Ben Halloran and defender Jordan Elsey netted the goals in a typically professional showing from the Reds at Kingston Heath in Melbourne's south-east on Friday night.

The Victorian side, conquerors of A-League side Wellington Phoenix in an earlier round, made Adelaide work hard until the final whistle but an upset seemed unlikely once the deadlock was broken.

The Reds dominated goalscoring opportunities against the part-time opponents, yet it was Bentleigh who had a golden opportunity to open the scoring but Paul Thurtell was unable to fully connect with a volley after a mistake from goalkeeper Paul Izzo.

From there on it was Adelaide who had the best sights of goal leaving Izzo a spectator for long periods.

Adelaide were without key attacking outlets Ryan Kitto and Craig Goodwin, the latter having scored in all three previous rounds of the cup.

Papa Diawara should have given Adelaide the lead, before Halloran converted from close-range on 20 minutes after George Blackwood had set up the opportunity with a penetrative run into the penalty area.

There were further opportunities for Diawara and Halloran before half-time while Bentleigh goalkeeper Ryan Scott was forced to pull off an athletic save on the stretch.

Defender Jordan Elsey doubled the advantage three minutes into the second period after Scott was unable to hold Isaias's awkward freekick.

"Bentleigh pushed all the way in the end and credit to them," said Halloran.

"We didn't do too well (in the early stages) trying to get control of the midfield and the match went back and forth."

The first team to reach three cup finals, Adelaide will face the winner of Saturday's derby between Western Sydney Wanderers and Sydney FC.

Adelaide lost last season's FFA Cup decider against Sydney FC in extra time, having won the maiden edition of the competition in 2014.

Australian Associated Press