The National League promotion hopefuls shocked League One AFC Wimbledon
An early goal from Tyrone Marsh and a late strike from substitute Adrian Clifton sent the League One Dons spinning to a 2-0 defeat.
The Dons, who in their previous incarnation caused probably the biggest shock of them all when they beat Liverpool in the 1988 final, for once found themselves on the wrong end of a cup surprise.
It was a memorable afternoon for Garrard, who as a player made more than 100 appearances for Wimbledon and helped them to two promotions.
Garrard said: “I’m on top of the world. It is my biggest achievement as the manager here for six years. It hasn’t sunk in yet.
“It’s full credit to the players, I can’t describe it. They threw everything at us but we are good defensively and well drilled.
“I feel for them, it was a proper FA Cup tie with the wind and rain, and the players will, of course, enjoy tonight.”
Wood, pushing for promotion to the Football League have yet to concede a goal in the FA Cup this season and are unbeaten at home.
They showed why with a resilient display at the back sprinkled with a touch of class up front from Marsh.
In the 10th minute a through-ball from Josh Rees split the Wimbledon defence and sent Marsh racing through on goal.
The 28-year-old former Macclesfield and Stevenage forward had to check his run and cut inside Nesta Guinness-Walker before lashing a powerful shot into the far corner.
Wood reached the same stage of the competition last season but their defeat by Millwall was played in front of no fans, so the majority of the 3,500 crammed into Meadow Park enjoyed this goal all the more.
After the break the rain began teeming down to soak the already glum away fans in the uncovered south stand, while it was the home side who looked more likely to score the game’s second goal.
It came with four minutes to go, Jacob Mendy providing the cross for former gas fitter Clifton, who had been on for a matter of seconds, and he flicked home at the near post to seal a deserved win.
“We started bright enough and we thought we were going to stretch them, but then we conceded the goal,” said Dons boss Mark Robinson.
“After going 1-0 down I still thought we’d have enough about us to create chances, but we didn’t.
“They were really well organised and we didn’t have enough craft or guile to create enough, which is disappointing.
“A few players went off and did their own thing, which can happen when you’re young and I need to talk to them about it.
“With contrast, they’ve got very experienced players, so they knew exactly what they were doing.”