Besart Berisha and Alessandro Diamanti returned to the starting eleven, while Ryan Scott held his place between the sticks. Fellow goalkeeper Filip Kurto returned via the bench.
Luke Duzel made it three straight starts after an impressive performance last week against Brisbane.
Macarthur could have had an early lead after Connor Pain’s poor touch allowed Ivan Franjic to shoot into an empty net. Pain was relieved after Franjic’s shot went wide.
It was United who opened the scoring through Dylan Pierias.
Pierias cut in on his left before curling his shot into the top corner for his fifth goal of the season.
Macarthur worked their way back into the game and eventually found an equaliser.
Matt Derbyshire’s clinical header looped over Ryan Scott to make it 1-1.
The Bulls took the lead just prior to half-time with another header – this time Markel Susaeta found the back of the net from close range.
United thought they had an equaliser 10 minutes into the second half when Berisha finished a one on one, but he was ruled offside.
Lachie Wales had a good chance to level things up, forcing a strong save from Federici with a shot inside the area.
Macarthur held on for a 2-1 home win in the rain.
United travel to Queensland for a clash with Brisbane Roar on Saturday, 27 March.