It was a night to forget in Nailsworth as Cheltenham Town suffered a heavy defeat by Forest Green Rovers in the Checkatrade Trophy.
The Robins were quite simply second best all night to their nearest rivals and must dust themselves down quickly before travelling to Northampton Town for Saturday's important League Two match.
Milton had named a competitive team, making only three changes from Saturday's side.
One was enforced through the illness of Scott Flinders which meant that Rhys Lovett stepped up for the first time this term with youth product Freddie Tapworth taking his place on the bench.
There were full debuts for Chris Clements and Kelsey Mooney at the expense of Nigel Atangana, a second half substitute, and Jacob Maddox.
The home side were positive from the outset and forced the Robins into all the defending in the opening exchanges, breaking the dealock through Grubb with only 14 minutes on the clock.
Over came a corner from the left, Boyle cleared and the former Weston-super-Mare man smashed it home from the edge of the box.
Campbell added the second three minutes after the restart, again it originated from a corner kick down the Forest Green right.
The midfielder picked up the loose ball and lashed it past Lovett from 25 yards to extend the lead.
Number three arrived five minutes from time, George Williams racing onto Tahvon Campbell's threaded pass and squeezing the ball past Lovett from 18 yards.
Substitute Isaac Pearce completed the misery in injury time, bursting through the middle before beating Lovett from the edge of the box.
FOREST GREEN ROVERS (4-4-2): Montgomery; Shephard (Collins 46), McGinley, Digby, Archibald; Campbell, Worthington, Winchester (Brown 64), Grubb; Williams; Morris (Pearce 69). Subs not used: Sanchez, Laird, James, Gunning.
CHELTENHAM TOWN (4-4-2): Lovett; Forster, Mullins, Boyle, Field; Dawson (Atangana 46), Clements, Jones (Kalala 78), Broom; Duku (Barnett 57), Mooney. Subs not used: Lapworth (Gk), Tozer, Lloyd, Baldwin.
REFEREE: L Swabey
ATTENDANCE: 1,074 (236 from Cheltenham)