Top-of-the-table Nottingham Forest suffered only their second defeat of the season as Scunthorpe produced a superb display to win 4-0 at the City Ground.
Colin Calderwood's side entered the lunchtime kick-off having claimed four clean sheets in their previous seven outings, but looked strangely out of sorts in front of their home fans as the visitors dominated throughout.
Cleveland Taylor was the first to score for Brian Laws' men as he took advantage of some hesitant defending from Gary Holt to fire past Paul Smith on 28 minutes.
If the home crowd were looking for a response they were to be disappointed as, inside six minutes, The Iron strengthened their position when Andrew Keogh finished off a nicely worked move involving strike partner Billy Sharp as he ventured into the box and finished neatly.
Scunthorpe were showing they can be considered real candidates for promotion as they moved to within three points of top spot, and the win was secure when Ian Morris stroked the ball home through the legs of a defender after more neat interplay between Keogh (pictured) and Sharp.
The Iron attack looked a class apart and Sharp finally got the goal his efforts deserved four minutes into injury time as he spun in behind Wes Morgan and latched onto Ian Breckin's back-header to make it four.
Bristol City could have moved equal with Forest at the summit of League One but their 1-1 draw away at Brentford still elevated them into second.
City boss Gary Johnson saw his troops take the lead through Jamie McCombe four minutes before half time, but The Bees rallied and Kevin O'Connor's penalty after 68 minutes ensured the spoils were shared.
In what was perhaps the game of the day at Gresty Road, Crewe Alexandra scored twice in the last five minutes to beat a shell-shocked Gillingham 4-3.
The visitors had looked in firm control when Alan Pouton (21) and Michael Flynn (28) scored in the first half hour, and even when Nicky Maynard pulled one back (36) Gillingham restored their two-goal advantage through Dean McDonald (48).
However, Dario Gradi's side showed remarkable spirit and after Rodney Jack (68) gave them hope, Daniel O'Donnell (88) and Luke Varney (90) completed a sensational comeback.
Millwall's revival under caretaker boss Willie Donachie continued with a fine 2-1 away win at high-flying Carlisle.
The Cumbrians started the day in sixth place but fell behind at Brunton Park when Alan Dunne scored for the Londoners after 27 minutes.
Even though Jermaine Beckford equalised six minutes later on his debut after a loan move from Leeds, Millwall made it seven points from three games when Poul Hubertz netted on 39 minutes.
Bradford City slipped up at home to Yorkshire rivals Huddersfield when Mark Hudson's 25th minute strike condemned them to a 1-0 defeat.
The Terriers held on for all three points despite going down to ten men when Danny Adams was dismissed for two bookable offences on 72 minutes.
The game between Leyton Orient and Chesterfield at the Matchroom Stadium ended in a goalless draw.
Click below for individual match summaries:
Bradford City 0-1 Huddersfield
Brentford 1-1 Bristol City
Carlisle United 1-2 Millwall
Crewe Alexandra 4-3 Gillingham
Leyton Orient 0-0 Chesterfield
Nottingham Forest 0-4 Scunthorpe