Toothless Southend dropped out of the League Two automatic promotion places after defeat against Aldershot.
Danny Hylton nodded in Chris Barker's cross for the only goal of the game and his 15th of the season.
A smart save from Cameron Belford prevented Peter Vincenti from making 2-0 soon afterwards, as Southend struggled to impose themselves.
Lee Hills' cross-shot was palmed to safety in the first half, but that was all the hosts could muster.
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Southend United manager Paul Sturrock told BBC Essex:
"For the first 45 minutes, we played some decent football but the final pass, the final cross, the final finish, let us down.
"In the second half, they scored with their one chance in the game.
"I've got to give them credit, they worked very hard. I don't think their goalie's had a save (to make) and we're the home team - that's what disappoints me."
Aldershot boss Dean Holdsworth told BBC Surrey:
"The team have shown in the last two performances you've got to have all the ingredients to win a football match. We came here to Southend, who've been fantastic over the season, and knew it would be a tough game.
"The game plan was to make sure it was difficult for us to be broken down and at some point we'd get a chance, and when that moment came we'd have to take it.
"Over 95 minutes the players worked their socks off. We put out bodies on the line. I'm delighted with them."