Millwall moved into the quarter-final of the FA Cup for the first time since their run to the final in 2004 with a 2-0 win at non-league Luton.
The Championship side avoided the potential banana skin thanks to first-half goals from the excellent James Henry and on-loan striker Rob Hulse before substitute Dany N'Guessan netted a third just before the end.
Blue Square Premier side Luton had caused a huge upset in the fourth round when they won at Premier League side Norwich but lacked a clinical edge up front despite an energetic display.
Luton spent more time attacking than defending in the opening 45 minutes but Millwall always looked more dangerous when venturing forward.
The Londoners took some of the pressure off themselves after just 12 minutes when Henry gave them the lead but the goal was a complete gift from the Luton defenders.
Hungarian defender Janos Kovacs was the guilty party as he mis-controlled a ball that flew at him and then hesitated looking for somebody to clean up the mess. Instead it was Henry who nicked in to get around keeper Mark Tyler before rolling the ball into the empty net.
Henry was the creator of the second goal in the 36th minute too. The 23-year-old winger - who has been linked with Aston Villa – did superbly down the right before standing up a cross to the back post. Hulse, on loan from Queens Park Rangers, headed the ball up in the air and then produced an unconventional looking bicycle kick that looped up perfectly into the corner of the net, despite appearing to be mishit off his shin.
Luton did play decently in the first-half and enjoyed spells of pressure but struggled to create too many chances.
Andre Gray looked lively up front but their best chance of the half fell to Guinea-Bissau midfielder Arnaud Mendy in the 18th minute. Millwall failed to deal with a free-kick looped into the box and the ball fell nicely for Mendy, who fired a half-volley on target only for Irish international keeper David Forde to make a great save.
Luton would have been hoping for a barnstorming start to the second half but they initially struggled to get going.
However, they did have a good spell of pressure for around 15 minutes either side of the hour mark. In the 54th minute Gray outsprinted his man and Forde had to be alert to save with his feet on the edge of the area.
Luton decided to bring on strikers Stuart Fleetwood and Jon Shaw to try and get a goal back but the added forwards worked against them.
With too many men up field they struggled to get, and then hold on to, possession, and Millwall streamed forward to exploit the extra space.
Andy Keogh twice came close to scoring but they finally sealed the win with four minutes remaining when N'Guessan swept home after Tyler failed to hang on to a shot from fellow Millwall substitute John Marquis.
Luton pushed forward once more but Millwall were well disciplined and earned a clean sheet as well as a place in the last eight of the Cup.
MAN OF THE MATCH
James Henry (Millwall) – The 23-year-old showed why Premier League clubs have been watching him with an outstanding performance.
Luton Town: Tyler 6, Taylor 6, Henry 6, Kovacs 4, Howells 5; Lawless 6, Smith 6, Mendy 6, O'Donnell 5; Gray 7, Rendell 6. Subs: Shaw 5, Fleetwood 5,
Millwall: Forde 8, Dunne 6, Osborne 6, Beevers 7, Lowry 6; Henry 9, Abdou 6, Trotter 6, Feeney 6, Hulse 7, Keogh 7. Subs: A.Smith N/A, N'Guessan 7, Marquis 6.