The last unbeaten league record in England is no more. Leeds United lost for the first time this season yesterday, in fact for the first time in the Premiership since May. What's more, it was only their third league defeat in the calendar year and came against a club that had not beaten them in the top flight since 1980.
All in all, something of a surprise then, one that meant that Liverpool top the Premiership and that Alex Ferguson is probably a very happy man indeed.
Only one win now separates the top six in this freshly interesting division, and it is a measure of how condensed matters are that Sunderland's victory brought them to within seven points of Liverpool, whom they visit next Sunday.
Leeds are on the same points as Liverpool in second place, having played one match more.
Even though there was understandable disappointment from David O'Leary's perspective at this first defeat, the Leeds manager accepted this was one of those days when "it wasn't going to be".
His players had not performed badly or without effort, but the loss allowed O'Leary to again state his belief that his squad is too small to challenge Liverpool, Manchester United and Arsenal. "We're at the max," O'Leary said.
O'Leary was referring to how he and Brian Kidd are getting the most out of the Leeds squad - "extending the players" was O'Leary's phrase.
But while they missed Harry Kewell and Mark Viduka because of World Cup commitments, and Lee Bowyer and Jonathan Woodgate for other reasons, their absence also served to highlight Leeds' strength.
Lucas Radebe is back in training, and Seth Johnson, a £9 million sterling purchase from Derby County, made his full debut yesterday. So O'Leary's plea has to be seen in context.
As does yesterday's match. Had Robbie Keane buried a 21st-minute chance when released by David Batty's superb pass, the afternoon could have been totally different. But Thomas Sorensen made a good save, the first of three by the Dane, Sunderland regrouped around the excellent Gavin McCann and held out until half-time.
And it was a case of holding out. No one personified that defiance more than Emerson Thome. Up against the horrible beauty that is Alan Smith, Thome used all means possible against the striker. That this included a 17th-minute stamp on the prostrate Smith which went unnoticed by both referee Graham Barber and his linesman was most lucky for the Brazilian. In mitigation, Thome had just been clocked by Smith.
Their explosive contest was the highlight of the first half. With Batty orchestrating affairs, Sunderland had not forced a save from Nigel Martyn - although Olivier Dacourt cleared a Darren Williams header off the line in the fifth minute. But that changed just 90 seconds after the interval when Martyn dived low to parry a swerving shot from Jason McAteer. The ball spilled to Julio Arca at the far post and the Argentine swept it in.
That minor setback became a major one seven minutes later when Kevin Phillips was involved in his first meaningful action of the day. He ran on to a perfect chest pass from Niall Quinn and struck an exquisite, instant volley beyond Martyn. It was some goal, Phillips' seventh of the season, and he celebrated like a man who knew Tord Grip was in the stands.
Sunderland began to relax and played some decent football thereafter. But Leeds never let up. Sorensen made another important stop from Keane five minutes later, and then with 20 minutes to go Keane went down under a challenge from Bernt Haas. Everyone, Peter Reid included, thought it was a penalty, but referee Barber ignored the appeal and booked Keane for diving. Barber had a dreadful game, but even repeated TV replays could not prove that Haas made contact.
Barber then missed a Martyn fingertip on to the crossbar from a McAteer free-kick as the play swung from end to end and, at the final whistle, O'Leary confronted the official. It was just another small battle lost yesterday. But, like the missing four, they will return.
SUNDERLAND: Sorensen, Haas, Thome, Williams, Gray, Arca, McCann, Thirlwell, McAteer (McCartney 87), Quinn (Laslandes 69), Phillips. Subs Not Used: Macho, Schwarz, Butler. Booked: Quinn. Goals: Arca 48, Phillips 55.
LEEDS: Martyn, Harte, Matteo, Ferdinand, Mills, Johnson, Dacourt, Bakke, Batty, Smith, Keane. Subs Not Used: Kelly, McPhail, Wilcox, Duberry, Robinson. Booked: Mills, Keane, Smith.
Referee: G Barber (Tring).