Below-par Walsall slipped to third in League One after suffering a surprise defeat against Rochdale.
Ian Henderson gave Dale an early lead and Calvin Andrew added a second-half brace to condemn the Saddlers to a first defeat in eight matches.
The result also ended Sean O’Driscoll's perfect start as Walsall head coach and halted a run of five consecutive league wins.
Walsall made one change to the side that won 2-0 against Peterborough in the final match of 2015, with Anthony Forde coming in for Sam Mantom.
Keith Hill’s Rochdale made a blistering start and almost took the lead after just ten seconds, when Henderson’s audacious chip was tipped over by home keeper Neil Etheridge.
Calvin Andrew hooked marginally over from the resulting corner, but Walsall’s reprieve proved short-lived as Dale took a deserved third-minute lead.
Andrew Cannon did superbly on the right, jinking to the byline and cutting the ball back for Henderson to fire a low first-time shot past Etheridge.
And rampant Rochdale went close to extending their lead shortly after, Cannon seeing a 20-yard drive kept out by Etheridge at his near post.
Walsall were second best throughout the opening period and struggled to fashion any clear-cut chances.
Forde dragged a weak effort wide from the edge of the box, and George Evans saw a 20-yard drive blocked, but that was as close as they came.
And it was a physical and hardworking Rochdale outfit who looked the more likely to get the next goal.
On 28 minutes, the lively Cannon skipped inside Andy Taylor before firing into the side-netting from a tricky angle.
Peter Vincenti’s long-range strike was held by Etheridge, who also made a spectacular one-handed stop from Henderson’s header – although the flag was up for offside.
HALF-TIME: WALSALL 0-1 ROCHDALE
Rochdale, who were winless in their previous eight visit to the Banks’s, continued to enjoy the better of proceedings at the start of the second half.
On 52 minutes, Andrew’s powerful strike looped up over James O’Connor but the back-peddling Etheridge made a fine tip-over save.
And then from the subsequent corner, the ball ricocheted into the path of McDermott, who lashed inches wide from eight yards.
But Dale weren’t to be denied just before the hour mark, as Andrew made it 2-0 with a glancing header from McDermott’s near-post corner.
Rochdale were relentless and on 69 minutes, Henderson saw a right-footed drive parried by Etheridge.
And the visitors added a third goal with 13 minutes remaining, McDermott crossing low for Andrew to calmly side foot home from ten yards.
Walsall were badly out of sorts and only registered their first shot of the second half on 83 minutes, Evans firing well over from outside the box.
Moments later, it should have been 4-0.
McDermott dribbled past three Walsall players and crossed for Andrew, who was somehow denied by Etheridge, before O’Connor blocked Henderson’s follow-up.
Rochdale continued to force the initiative, with the impressive McDermott latching onto Andrew’s flick-on before testing Etheridge from range.
Evans curled a free-kick over deep in stoppage time for well-beaten Walsall, who had a day to forget.
FULL-TIME: WALSALL 0-3 ROCHDALE
Team: Etheridge, Demetriou, Downing, O’Connor, Taylor (Henry 73'), Chambers, Evans, Forde, Lalkovic (Bradshaw 59'), Sawyers, Cook (Morris 45').
Subs not used: Mantom, Preston, Kinsella, Roberts.
Attendance: 4,857 (375 Rochdale supporters).