A strike by the in-form Ryan Campbell on 55 minutes was enough bring Christmas joy to Ferney Park on Saturday.
The goal earned Ballinamallard the vital points in their quest to pull away from the relegation area.
It was Campbell’s third goal in a week and keeps the Fermanagh side out of the drop zone.
The goal came after McMenamin, playing in an unaccustomed midfield holding role, set up dangerman Liam Martin, and when he crossed Campbell was on hand to steady himself before shooting past keeper James McGrath from 10 yards.
Ballinamallard manager Whitey Anderson described his side’s performance as “top drawer”.
He added: “I’m absolutely delighted for the players. We had a tough time on Tuesday night and they were down a little but I told them to stand up today and be counted and I thought they were brilliant from the first minute to the end.
“I don’t think anybody could deny us the three points today.
“Liam Martin was very lively up there today and for Ryan Campbell, that’s four goals in recent games and he took the goal really well with his left foot.
“It was a cracking goal and we were unlucky not to score a couple more near the end. Jason McCartney and Johnny Lafferty were very unfortunate. But I’ll take the 1-0.”
Glenavon manager GAry Hamilton who had to watch the game from the stand, felt his side had one of their better games in recent weeks.
“We played some good stuff and had four or five good chances from six or seven yards out,” he said.
“Two months ago they would have been finished and the game would have been out of sight, but when confidence is low and things aren’t going your way they don’t go in.”