Lincoln City 1-2 Welling United
Two goals in three first-half minutes from Josh Wakefield and Harry Beautyman helped Welling beat in-form Lincoln.
The Imps had taken an early lead through Kris Bright before Welling's two strikes turned the game around.
Wakefield shot into the top corner after 37 minutes before Beautyman's 20-yard drive, five minutes before half-time, fired Welling in front.
Alan Power might have grabbed a point for Lincoln late in the second half but sent his effort wide of the post.
It was Lincoln's first defeat in six games.
Welling United boss Jamie Day told BBC Radio Kent:
"I'm really pleased with the performance apart from the first 20 minutes. After that we bounced back, showed good character and I felt we deserved the win.
"Their keeper kept them in it. I thought he pulled off a couple of really good saves.
"It was a bit unfortunate we couldn't pick up another one and seal the game in the last 10 minutes.
"We could finish in the top 10. It depends on injuries and confidence but hopefully we can achieve that."