JACK Defty's 20 yard blockbuster - the 49th goal under manager Tommy Taylor ensured Lynn made their fifth semi-final in six years in this competition.
The Linnets again made hard work of the win.
Matt O'Halloran played 80 minutes on his debut and showed a willingness to take people on.
Defenders Simon Clark and Adam Jones sat it out, which gave Stephen Harvey his first start of the campaign.
Taylor said: "Jack scored a very good goal. I took him off to keep him fresh for Saturday.
Harvey was excellent. The more match fit Matt gets, the better he will be.
"We should have been three up at half-time, and we were steady at the back."
The Linnets made their intentions clear early on, Mark Angel forcing a stinging save from Justin Bray, who made an even better one at point-blank range from Gary Setchell, but the rest of the game was flat by comparison.
The Division One West strugglers - a very big side playing all in white - had a touch of the Boltons about them, but none of the physical presence up front. They played one up front and didn't force stand-in keeper Jon Higgs into a serious save.
Forty seconds into the second half Danny Bloomfield's header bounced inches past the post.
Sub Robbie Harris' first touch almost earned a penalty, but two minutes later Defty convincingly fired home a loose ball into the bottom corner of the net.
Fog descended in the last 20 minutes and visibility was very poor when in injury time Bray's heroics denied Angel and Harris.
Darran Hay, named on the bench, did not turn up.
Taylor said: "He had problems getting to the game. It's a shame as he can't play on Saturday and I would have used his legs and saved other people's."
Lynn: Higgs, Harvey, Setchell, McMahon, Hammond, O'Hollaran (Quistin 80), Camm, Defty (J. Wilson 76), Bacon (Harris 62), Bloom field, Angel. Sub not used: S. Wil son. Goal: Defty 64.
Sutton Coldfield: Bray, Joners (Jonathon Rowe 76), Wilson (D Rowe 82), Spittle (Fuller 69), Geohaghan, Pierrepoint, Grocutt, Barker, Justin Rowe, Woolsey, Coates. Not used: Ling, Keogh
Bookings: Grocutt 28, Pierre point 57.
Referee: T Howes (Norfolk)