The National League North outfit picked up a huge scalp in the form of Championship giants Derby County on Saturday lunchtime.
Connor Hall headed home from a corner after just 10 minutes at Victory Park before Mike Calvelely converted a delicate cross six minutes from time to double their lead.
Derby’s team consisted of Under-23s and Under-18s players, however, due to a Covid outbreak in their camp this week.
Wayne Rooney and Derby’s first-team stars could not play, let alone travel to Lancashire, due to having to self-isolate at home.
But Chorley still had a job to do to progress to the fourth round of the competition and they did themselves proud with a dogged performance.
They've already knocked out League One teams Wigan and Peterborough.
And Chorley will now be dreaming of a once-in-a-lifetime Premier League showdown later this month.
The fourth and fifth-round draws takes place on Monday night prior to West Ham’s game away to National League side Stockport County on BT Sport.
Chorley goalscorer Hall told BT Sport: "Unbelievable feeling! That will keep us going for a long time. We played so well, top effort from us and we're so excited.
"We have to show them respect. At the end of the day, they're full-time pros as well. They're not going be a push pushover.
“We started off well and we just needed to keep pushing on, getting the second was great.”
On who Chorley would like in the fourth round: "Obviously one of the biggest teams in England. I'm a Newcastle fan, so I'd love to play against them but hopefully someone like an Arsenal in the next round."