Welwyn Garden City survived a second-half fightback from Mulbarton Wanderers to book their passage to the next stage of the FA Cup.
Goals from Callum Taylor and Jordan Watson had given Welwyn a solid half-time lead but Ben Thompson halved the deficit in the second period.
It became a proper cup tie in the closing stages, not helping the nerves of the home faithful at Herns Lane.
But Welwyn came through unscathed to clinch a 2-1 win.
Their reward will be a trip to Bedford Town in the second qualifying round after they beat Canvey Island in their replay courtesy of a last-minute winner.
Manger Nick Ironton made four changes for this one. Joe Bennett, Lee Close, Jordan Kinoshi and Charlie Payne were all given a starting place as they replaced Dave Keenleyside, Elliot Bailey, Matty-Campbell-Mhlope and Cyrus Babaie.
The Norfolk-based visitors went for two differences to Saturday's draw, Tom Hislop and Matt Doyle coming in for Cain Eagleton and Danny Self.
There was a small feeling among some Citizens fans that they had got out of jail by taking the tie to a replay and they would have therefore been delighted to reach half-time with a good lead.
It was a deserved advantage too as they pressed for the majority of the half.
WGC found Mulbarton's Tom Wright in just as good form as he was in their first meeting and the keeper made two superb saves inside the first 10 minutes.
The first was to palm a volley from Charlie Payne away from his left-hand corner while the second was just incredible.
It looked for all the world as if Kinoshi had knocked the hosts into the lead with a close-range shot at the back post.
Wright though had other ideas as he flung himself across the goal to stop the effort with his leg.
Payne also had a free-kick over the top and Jess Walklin almost scored with a tackle that was so strong it sent the ball towards goal, the keeper getting down to save.
But the goal did come thanks to some great work on the right by Kinoshi.
It seemed as if the chance had gone when the defender came out quickly to meet him.
But he remain composed and a lovely dinked cross from the right was flicked into the net by the head of Taylor.
Welwyn were their own worst enemies at times and although they were still well on top, the visitors got forward much more as the half came to a close.
For that reason a second was most welcome and again it came from Kinoshi's trickery on the right.
He got right down to the corner flag but with two defenders near him, his path seemed blocked.
One wriggle later he was in the box and his low cross was controlled and hit home by Watson.
It was a needed second at the time and came to carry even more meaning when Mulbarton pulled one back nine minutes after the restart.
It came after a brief spell of pressure and after a free-kick had been only partially cleared and Danny Beaumont's delivery from the following corner was bang on the money for Thompson to head home.
The response from the City bench was to introduce Jon Sexton and the response on the pitch was equally positive.
Watson poked an effort wide and then Sexton delivered a peach of a cross that Taylor flicked over Wright but off the crossbar.
Jay Rolfe then headed a corner over as Welwyn looked to restore their two-goal advantage.
The game felt much more like a cup tie at this point, the intense heat of the day a far cry from John Motson and his sheepskin in a snow storm.
And with only a goal in it, the Eastern Counties Premier Division visitors fancied their chances.
They had pressure but Taylor could have made things safe with 18 minutes to go. Wright yet again had other ideas though as he kicked the low drive behind.
The resulting corner was flicked across goal and wide by Ryan Doherty.
The final 10 minutes were tense, more than they probably should have been but the biggest scare for Welwyn was a handball shout against Close that was ignored.
Kinoshi and substitute Keenleyside could have settled it within seconds of each other, Wright making the stop.
And they kept Charlie Crowley from facing anything of note in the four added minutes to move on.
WGC: Crowley, Bennett (Sexton 55), Doherty, Walklin, Close, Rolfe, Kinoshi, Spaul, Watson (Keenleyside 73), Payne (Bailey 67), Taylor.
Subs (not used): Vasey, Campbell-Mhlope, Babaie, Wade.
Goals: Taylor 21, Watson 45
Booked: Bennett 27, Taylor 66
Mulbarton Wanderers: Wright, Doggett, Oliver, Page, Easton, Hislop, Doyle (Altay 79), Jones (J.Smith 46), Thompson, Whiting (Henry 59), Beaumont.
Subs (not used): Eagleton, K.Smith, Self.
Goal: Thompson 54
Booked: Beaumont 81, Tom Hislop FT
HT: Welwyn Garden City 2 Mulbarton Wanderers 0
Referee: Graham Swanton (Sawbridgeworth)
Attendance: 211
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