Newcastle United's nine-game winning run was brought to an end at St James's Park by Blackburn Rovers.
A second-half goal from Charlie Mulgrew saw Owen Coyle's side win 1-0 this afternoon.
United had been looking to post a record 10th successive victory in all competitions against a team which had been third-bottom in the Championship at the start of the day.
But Rafa Benitez's side, so confident and composed against Leeds United at Elland Road six days earlier, were inexplicably poor and visiting goalkeeper Jason Steele had little to do.
The game also saw Jesus Gamez stretchered off injured on what was his full league debut for the club.
Elsewhere, second-placed Brighton and Hove Albion came from behind to beat Fulham 2-1 at the Amex Stadium to narrow Newcastle's lead at the top of the Championship to two points.
Benitez, possibly with Tuesday night's EFL Cup quarter-final against Hull City at the KCOM Stadium in mind, made six changes for the game.
Aleksandar Mitrovic, Jesus Gamez, Chancel Mbemba, Christian Atsu, Isaac Hayden and DeAndre Yedlin came into the starting XI.
Surprisingly, captain Jamaal Lascelles and leading scorer Dwight Gayle were left on the bench by United manager Benitez.
Blackburn made the better start, and United had Karl Darlow to thank for an early save from Gateshead-born Danny Graham.
Darlow did well to tip over a looping header from the former Sunderland striker in the fifth minute.
Newcastle found Blackburn to be awkward opposition, and Benitez, possibly aware Brighton had gone behind against Fulham, didn't hide his frustration on the touchline as his players struggled to keep hold of the ball.
There were a few signs of life from United as the half wore on, and Christian Atsu had a 29th-minute shot deflected wide after good work on the right from Yedlin.
Jonjo Shelvey, wearing the captain's armband, attempted to get his team going as the half-time break neared, and Mitrovic, a peripheral figure up to then, put an attempted overhead kick well over Jason Steele's goal in the 41st minute.
Benitez sent out an unchanged after the interval, and Atsu and Hayden put chances wide early in the second half.
Newcastle then lost Gamez to injury. The 31-year-old was stretchered off in the 55th minute and replaced by Paul Dummett, who delivered telling ball for Matt Ritchie which was put over the bar by the winger.
Steele turned a shot from Shelvey round his post in the 69th minute as United pressed for a goal.
But the breakthrough was to come at the other end of the pitch.
Mulgrew prodded home a corner from Craig Conway in the 75th minute.
Leading scorer Gayle was sent on in the 85th minute, but he put the one chance that came his way over the bar.
NEWCASTLE UNITED: Darlow; Yedlin, Mbemba (Gayle, 85), Clark, Gamez (Dummett, 55); Shelvey, Hayden; Ritchie, Perez, Atsu; Mitrovic. Subs: Sels, Lascelles, Anita, Diame, Gouffran.
BLACKBURN ROVERS: Steele, Marshall, Lenihan, Mulgrew, Williams, Feeney, Lowe, Evans, Conway, Graham, Gallagher (Emnes, 63). Subs: Raya, Stokes, Akpan, Nyambee, Brown, Bennett.
Goal: Mulgrew 75
Bookings: Conway 24, Lowe 68, Hayden 83, Marshall 90
Referee: David Coote (Nottinghamshire)