The Blues had four goals at the half, but came home with a wet sail, sliding another nine goals past the Rams' custodian to complete a 13-0 rout.
United coach Sheridan Fairless said it was a great way to start the finals series.
“We were pretty stoked and it was nice to come away with a good win in the first week of finals,” she said.
“We're definitely happy and there were some mixed results in the rest of the competition that were very, very interesting. We're looking forward to the next couple of rounds.
“We just weren't converting (in the first half), we had plenty of opportunities, but just couldn't find the back of the net. We played really well the whole game, the scoreline didn't really reflect the chances we had in the first half.”
Sophie Papalia led the scoring with six goals taking her tally to 54 for the season, but plenty of her mates got on the scoresheet too with Caitlin Georgiou, Maria Villani (two goals each), Taylor Zito, Sarah Loverso and Hayley Cadel all finding the back of the net.
Fairless said Papalia's display had been sparkling, but the whole team had looked the goods.
“Sophie is very, very crucial for us on the left wing, but there were some really good performances across the board,” she said.
“I would have said best-on-ground was Pippa (Grabham), she made some awesome overlapping runs of the left-hand side, she was really dangerous and created great opportunties.”
Two wins away from completing a perfect season, Fairless said her side could not afford to get ahead of itself.
“Obviously we're excited this time of year, the way the finals series is being played is a little bit different as a knockout cup and we haven't played that before,” she said.
“We're not taking anything for granted, our journey started Sunday and everything we achieved before then is irrelevant.”
But United will not be joined in the semi-finals by McEwen Reserve co-tenant Shepparton South after it copped a late goal to fall against Strathdale on Sunday.
The Southerners led in the blink of an eye through Alannah Scopelliti, with the classy markswoman scoring inside three minutes to give her side an advantage.
But the Blues would level after winning a penalty, Nicole Ford converting from the spot at the 15-minute mark for 1-1.
Neither could break down the other down until the game's dying stages, with Strathdale's Eva Harrington bobbing up in the 89th minute to win it for her side.
It ends a solid campaign from South where it finished fourth on the table, but struggled to match it with the league's big dogs.
The weekend's other winners were Colts United (1-0 v La Trobe) and Spring Gully (2-1 v Eaglehawk).
