Joel Randall scored twice in five minutes to fire Exeter into the FA Cup third round for only the third time in 18 seasons following a 3-2 victory at Gillingham.
Vadaine Oliver put the hosts ahead on 21 minutes after Alex MacDonald had dispossessed Lewis Page inside the area.
But the League Two side looked comfortable throughout against a team 16 places and a division higher than them.
They trailed for just eight minutes before Nicky Law ended a neat move involving Randall and Ryan Bowman by firing low past Jack Bonham.
Law turned provider for Randall’s first goal as he intercepted Bonham’s poor clearance before teeing up the Grecians’ striker, who fired home from 12 yards.
The duo teamed up again to complete Exeter’s 11-minute turnaround as Randall latched onto Law’s cutback and cut inside to fire home.
Gills striker Dominic Samuel set up a nervy finale by hooking his shot past Jokull Andresson with 10 minutes remaining.
Randall struck the post from long-range when bidding for his hat-trick but Exeter did enough to win their third FA Cup away tie in 25 attempts.