Crawley striker Billy Clarke bagged his fifth goal of the season to dump Met Police out of the FA Cup - but they were forced to hold off a late fightback from the non-league outfit.
Goals from Josh Simpson and Clarke had put Richie Barker's men in command at Imber Court and all but booked their place in the next round.
Alan Tait's goal eight minutes from time for the Blues worried Crawley but they clung on to avoid a replay.
Four leagues separated the Ryman Premier minnows and the promotion chasing League One side and the gulf in quality showed early on as Dannie Bulman rattled the bar.
Sergio Torres then had an effort palmed away before Simpson broke the deadlock on 36 minutes, latching on to Michael Jones' throughball and poking past keeper Jamie Butler.
The Blues did improve after the break with Howard Newton forcing a smart save from Paul Jones and Craig Brown dragging an effort wide.
Clarke then looked to have made Crawley's progression into round two certain when he tapped home a second on 70 minutes.
Tait pulled one back after Brown's effort had come back off the bar but despite late pressure, which saw Newton hit the post, Crawley held on.