The Victory take on United at Skilled Park in the fourth versus fifth final which sees the loser dumped out of the finals race and Merrick said he will leave no stone unturned as he strives to qualify his side for their fourth A-League Grand Final.
Merrick said there was every possibility that he could deploy Archie Thompson and Carlos Hernandez with Danny Allsopp, Robbie Kruse and Marvin Angulo in a five-man attack.
"It's possible," Merrick said. "The way we play, we can do it. We can certainly play with five attacking-minded players. When we go into the finals we will be playing attacking football."
And Merrick was sweating on the fitness of key midfielder Grant Brebner who will be the link between defence and attack and could play a vital role if he is passed fit.
"Playing on the Sunday is good because it gives us more time to prepare and gives more time for Brebner and (Billy) Celeski to get right and Archie to get some more work under his belt," Merrick added.
"Billy is looking like he could play a part, but Brebs is not looking good. That may change during the week. This is Brebs' best season of the five seasons he's been here and it would be great to have him available.
"No doubt he'll get close and give himself a chance, but if he's not right we've got a lot of good players in the squad."