Eyemouth paid the penalty for a string of early missed chances, and a sending off, when they were beaten at Burntisland on Saturday.
The Fishermen started well and created at least half a dozen chances in the opening 15 minutes.
But poor finishing let them down, with shots either being driven straight at the home goalkeeper or hit high and wide.
They did make the breakthrough when a ball into the box by Connor Lough was parried by the keeper and it was forced home from close range.
But ten minutes later the home side equalised when they broke upfield and netted.
Worse was to follow for United when Lough was sent off, shown a straight red card for a tackle outside the box which was deemed as denying a goalscoring opportunity by the referee.
This meant Eyemouth had to play the whole of the second half with only ten men, and as legs began to tire, Burntisland took advantage, scoring twice to put the result beyond doubt.
Eyemouth did manage to create a couple of other chances, but these were also missed and the home side ran out comfortable winners.
As the season starts to wind down, Eyemouth now only have three games remaining, against Peebles, Berwick Rangers Reserves and Hawick.
Eyemouth: Tansey, Burrell (trialist), Phillips, Lough, Spiers, Adamson, Jess, Bullen, Collin, Faulkner, Raeburn (trialist).