The Victory vitally needed a win in their Round 4 clash with a Shane Smeltz and Joel Porter-less United outfit and the way they went about it pleased Merrick greatly.
"It's never an easy game. We were just happy that we controlled the game from the position," Merrick said after Robbie Kruse's first-half goal proved the difference.
"We ground it out which was important and it was a clean sheet.
"We've (lost an early lead) a couple of times, we did it against Sydney as well (as North Queensland)."
Merrick admitted his side had worked hard to shore up their defence after conceding seven goals in their first three outings and was happy it worked out away from home.
"We've done a lot on our set plays, because up until today we'd conceded seven goals but four of them were from set plays - two frees, a corner and a penalty," he added.
"We really wanted to get our discipline and marking at set plays right and it just worked a treat for us.
"I think a clean sheet was a bit of a bonus."