Cheltenham avoided an FA Cup shock as they gained a hard-fought win at Luton.
Darryl Duffy put the Robins ahead when he raced on to Scott Brown's goal-kick but Aaron O'Connor equalised when he converted from Robbie Willmott's cross.
Marlon Pack's solo effort made it 2-1 and O'Connor levelled with a powerful finish before Luke Summerfield's first-time shot restored the visitors' lead.
Duffy was sent off for foul language but Cheltenham scored again as Russell Penn finished off a counter-attack.
VIEWS FROM THE DRESSING ROOM
Luton manager Gary Brabin told BBC Three Counties Radio:
"I am disappointed. We could have won today. You dream of getting in the hat for the next round, and with the big boys coming in it's a bit harder to take.
"Cheltenham are on a roll at the moment and when you have got that belief, things fall for you. They only had five or six chances on our goal and put away four of them.
"I thought we played some really good football. We played on the front foot which is what I want us to do. We always looked like we were going to score goals today, but it's disappointing the goals we have conceded."
Cheltenham Town manager Mark Yates told BBC Gloucestershire:
"It was a great game. We weren't as good as we have been and I think that's credit to them.
"We know we've been in a real game against a really decent side. On chances I think we deserved to get through but they gave us one hell of a scare.
"Scoring the early goal made us a bit lax and not as sharp as we could have been. They (the players) really wanted to win today and I'm just delighted to be in the next round."