St Albans City boss Ian Allinson admits his side caused their own downfall as defensive mistakes resulted in their 4-0 defeat at Hampton & Richmond Borough on Saturday.
The Saints suffered only their fourth defeat of the National League South season but remain second in the table despite the setback.
Allinson said: "We've been the victim of our own downfall. We haven't defended properly.
"Individual mistakes have cost us and before you know it we're 3-0 behind and down to ten men. It was going to be very difficult to come back from that.
"We gave the fourth goal away by not really defending the corner properly but we were one man light at the time.
"Once the game got stretched out it was always going to suit Hampton because they're very good at breaking and have lots of pace going forward."
City fell behind in the 29th minute of the contest when Nicke Kabamba netted from close range after goalkeeper James Russell parried Brendan Kiernan's free-kick.
Hampton made it 2-0 six minutes into the second half when Russell failed to hold onto the ball from a home effort and Kabamba doubled his tally.
Any chance of a comeback was ended in the last 15 minutes after the Saints were reduced to ten men.
Tom Bender handled the ball in the area and was sent off. Tom Jelley's penalty was saved by Russell but he reacted quickest to net the rebound and make it 3-0.
The hosts completed the scoring late on when Kiernan fired home from close range.
Allinson said: "If you make individual mistakes, especially in the back four or the goalkeeper and get punished, it's going to cost you and hit you hard in the back side by the time you finish the game."
The Saints' squad is currently stretched and their manager hopes to bolster numbers by making a signing or two over the festive period.
He said: "I think we need to bring one or two personnel in this week to strengthen in the areas where we're lacking a little bit and try to keep one or two on their toes, because maybe one or two have just taken their foot off the pedal.
"I think we've got to. The squad was really at its thinnest with only a group of 16 or 17 so we need to look at bringing in one or two before January but we need to make sure they're the right players that can fit into what we're doing."
The Saints end the calendar year with a home game against mid-table Oxford City on Boxing Day.
Allinson said: "We're still second in the league and worked extremely hard to get to this position and now we've got to go and kick on again."