The Eagles started life in the new league away from home, travelling to Canterbury Park for the Sunday clash.
Neither side was able to gain a significant advantage early, both outfits slotting one goal in the opening 15 minutes.
United edged the behind count to lead 8-7, but Eaglehawk responded in the second to take a one-goal lead into the main break.
The Eagles would fire back after the interval with the only goal of the period and the sides went into the final term locked at 16 points.
But it was the Hawks who held up better down the stretch, firing through three goals in the final quarter to emerge 5.6 (36) to 3.8 (26) winners.
With both sides recording 11 scoring shots, United will feel better goal accuracy could have seen things turn out differently.
Harper Delamare led the way in front of the sticks for the Eagles, kicking all three of her side’s majors.
She featured on the best-on list, joined by captain Lily Dunham, Ruby Morgan, Mia Siede, Matilda Fowler and Jada Dennis.
United had the best performance of round one’s losing sides and sits sixth in the 10-team competition.
The Eagles will be at home for the first time this Sunday, facing early ladder leader and reigning premier Woorinen at Echuca South Recreation Reserve.