Chelsea were beaten 5-3 by a resurgent Tottenham Hotspur to stay top of the table merely on alphabetical order ahead of Manchester City on a day when a record 33 goals were scored in the English Premier League.
Young forward Harry Kane scored twice as Spurs, who have stuttered for much of the season in Mauricio Pochettino's first season in charge, ran rampant in front of home fans who have been starved of attacking football this term.
John Terry's late goal gave the scoreline a measure of respectability but the result is the latest dent to what looked like a runaway title charge by Jose Mourinho's men.
Chelsea are on 46 points, level on goal difference, goals scored and goals conceded with City, who had earlier beaten Sunderland 3-2.
Chelsea, previously beaten only once this season, looked set for another victory when Diego Costa scored after 18 minutes but rampant Spurs surged back with goals by Kane, Danny Rose and an Andros Townsend penalty to lead 3-1 at halftime.
Kane then fired in his second goal seven minutes after the restart and though Eden Hazard pulled one back, Nacer Chadli completed a memorable day for a hugely impressive Spurs with the fifth goal 12 minutes from time before Terry got a late third for Chelsea.
City and Chelsea have 46 points from 20 games, an identical goal difference of plus-25 and have both scored 44 goals.
Manchester United are third on 37 points after a 1-1 draw at Stoke City, Southampton are fourth on 36 after beating Arsenal 2-0, with Spurs up to fifth on 34.