Premier League leaders Liverpool crashed to their first defeat of the season at home to Southampton on Saturday, while Everton enjoyed a stirring 3-2 win at West Ham United.
Liverpool were without injured playmaker Philippe Coutinho, sidelined by a shoulder problem, but they came close to taking the lead in the first half at Anfield when visiting goalkeeper Artur Boruc produced a full-stretch save to keep out a Steven Gerrard free-kick.
Daniel Sturridge then had a penalty appeal turned down after tangling with Dejan Lovren, and it was Lovren who broke the deadlock in the 53rd minute with a backpost header from a left-wing corner.
Only a fine triple save from Simon Mignolet prevented Southampton from adding to their lead, but Lovren's goal proved enough to inflict a first league defeat on Liverpool since a 3-1 loss to the same side last March.
Everton now trail Liverpool by only a point after Romelu Lukaku scored on his debut to settle a thrilling game at Upton Park and help preserve the last unbeaten record in the division.
West Ham twice took the lead, via a deflected shot from Ravel Morrison and a Mark Noble penalty, only for Leighton Baines to level on each occasion with a pair of sensational free-kicks from 25 yards.
Noble was then sent off for a rash foul on Ross Barkley before Lukaku bravely headed home an 85th-minute winner in his first game since signing on loan from Chelsea.
Remy scores in losing cause Another on-loan striker, Loic Remy, scored twice on his first home start for Newcastle United, but the Frenchman still finished on the losing side in a 3-2 defeat by Hull City.
His 10th-minute header was cancelled out by Robbie Brady, who teed up Ahmed Elmohamady for a second equaliser early in the second period after Remy had curled home a second goal on the cusp of half-time.
Sone Aluko settled the match in memorable fashion with 14 minutes remaining, meeting George Boyd's left-wing cross with a sumptuous volley that crashed into the net off the right-hand upright. Stephane Sessegnon came back to haunt his former club Sunderland by scoring the opening goal in a 3-0 win on his debut for new side West Bromwich Albion.
A deadline-day signing from Sunderland, the Benin midfielder pounced in the 20th minute, before late goals from Liam Ridgewell and Morgan Amalfitano completed victory .
Earlier, Aston Villa lost key striker Christian Benteke to injury but still managed to snap a three-game losing streak with a 10 win at Norwich City