Match ends, Rochdale 1, Millwall 0.
Rochdale manager Keith Hill said the chance of facing Tottenham in the fifth round of the FA Cup is the "ultimate dream" after his side edged their fourth-round replay with Millwall.
Hill's outfit, who are second from bottom in League One, will now face the winners of Wednesday night's replay between Spurs and Newport County of League Two at Wembley.
The hosts adjusted better to the heavily sanded pitch which quickly cut up during a scrappy first half, as their Championship opponents struggled to create chances.
Captain Ian Henderson scored the only goal of a tight encounter, sweeping home from close range after collecting strike partner Calvin Andrew's pass.
Rochdale have now reached the FA Cup fifth round for just the third time in their history - doing so previously in 1990 and 2003.
Neil Harris' Lions, who are 32 places above Rochdale in the football pyramid, managed only one shot on target overall, and were also second best in terms of possession on a weather-ravaged surface.
"The finance is the stand-out reward - it's a chance to dream and a chance to play against Premier League opposition if Spurs beat Newport," said Hill.
"My head says let's play Newport, who we would respect, but my heart says let's play Tottenham.
"We would have to play at our very, very best and they would have to have an off day for us to have any chance, but that's the dream."
The Dale started brightly and went close to opening the scoring inside the first minute when midfielder Andrew Cannon volleyed wide.
They felt they should have got a penalty when Henderson was felled in the area as he attempted to get on the end of Joseph Rafferty's cross, but referee Tim Robinson waved their protests away.
Henderson, 33, persisted and made the breakthrough in the 53rd minute, after Millwall midfielder Fred Onyedinma had earlier seen his headed chance bounce onto the roof of the net.
Harris introduced Steve Morison and his second-top goalscorer Lee Gregory just after an hour in search of attacking impetus - but they were unable to prevent the Londoners being knocked out of the cup.
'Rochdale fans were a disgrace' - Harris
Millwall manager Neil Harris has called Rochdale fans who invaded the pitch after tonight's FA Cup tie "a disgrace".
Around 100 home fans ran onto the pitch after a 1-0 win for the League One relegation strugglers booked a fifth round tie with either Newport or Tottenham.
They goaded Harris and his players and then made for the 351 Millwall fans, who thankfully remained in their seats.
"I thought the Rochdale fans were a disgrace at the end," said Harris.
"As Millwall manager, I am not going to complain about fan bases. But the way it was managed at the end, the way our fans were goaded, wasn't quite right.
"My players were treated very badly and me, and the staff, were abused."
Harris said he would not be reporting the incident to the Football Association.
Rochdale manager Keith Hill said: "It was a difficult surface. It rolled flat which was perfect in a strange sort of way but it allowed us to play a little bit of football. We dealt with the opponent well regardless of the surface.
"A lot of good people put a lot of man hours into the pitch. It was best prepared by some honest hard working people who work for nothing and it was due to them we had a game tonight.
"I hope we can get it better because I don't want any negative pressure on the club. We do things right at this club and have good values. I don't want the pitch to be an embarrassment."
Henderson loves the Cup - the stats
- Five of Ian Henderson's last seven goals for Rochdale in all competitions have come in the FA Cup.
- Millwall have lost each of their last three FA Cup away games to lower league opposition - also losing 1-4 to Southend in 2014 and 0-4 to Bradford in 2015.
- Rochdale have reached the FA Cup fifth round for just the third time in their history - doing so in 1990 and most recently in 2003.
- Before tonight Rochdale had conceded eight goals in their last two FA Cup games at home against teams from a higher division, losing 1-4 to Stoke and 0-4 against Huddersfield last season.
- 27CannonBooked at 76mins
- 32KitchingBooked at 90mins
- 2McLaughlinBooked at 85mins
- 18TunnicliffeSubstituted forGregoryat 63'minutes
- 11FergusonSubstituted forMorisonat 63'minutes
- 10OnyedinmaSubstituted forJ Wallaceat 77'minutes
- 14J Wallace
- Tim Robinson
- Shots on Target
Second Half ends, Rochdale 1, Millwall 0.
Mark Kitching (Rochdale) is shown the yellow card.
Attempt missed. Ben Thompson (Millwall) right footed shot from outside the box is high and wide to the left.
Attempt blocked. Conor McLaughlin (Millwall) right footed shot from more than 40 yards on the right wing is blocked.
Corner, Rochdale. Conceded by Conor McLaughlin.
Attempt missed. Calvin Andrew (Rochdale) left footed shot from outside the box is high and wide to the left.
Delay in match Andrew Cannon (Rochdale) because of an injury.
Andrew Cannon (Rochdale) wins a free kick in the attacking half.
Foul by James Meredith (Millwall).
Conor McLaughlin (Millwall) is shown the yellow card for a bad foul.
Callum Camps (Rochdale) wins a free kick on the left wing.
Foul by Conor McLaughlin (Millwall).
Jimmy McNulty (Rochdale) wins a free kick in the defensive half.
Foul by Lee Gregory (Millwall).
Callum Camps (Rochdale) wins a free kick in the attacking half.
Foul by Steve Morison (Millwall).
Foul by Calvin Andrew (Rochdale).
(Millwall) wins a free kick in the attacking half.
Substitution, Millwall. Jed Wallace replaces Fred Onyedinma.