Chelsea's Diego Costa continued his stunning start to life in the Premier League with a hat-trick in a 4-2 comeback win over Swansea City on Saturday that left champions Manchester City staring up the table after a 2-2 draw at Arsenal.Costa, who now has seven goals from his first four league games, helped Chelsea come out on top against the only other team with a 100% record, after Swansea had taken the lead with an early own goal from John Terry.
City's Martin Demichelis scored with a late looping header for the champions after moments of sublime skill from Jack Wilshere and Alexis Sanchez had briefly turned the match in Arsenal's favour, following Sergio Aguero's opener.
Newcastle United's sorry start to the season continued with a crushing 4-0 defeat at Southampton, Tottenham Hotspur were held to a 2-2 draw at Sunderland and Everton beat West Bromwich Albion 2-0.
Leicester City grabbed their first win since sealing promotion, beating Stoke City 1-0, while Burnley and Crystal Palace played out a goalless draw.
Chelsea fans probably did not need reminding just how big an upgrade Costa was on his predecessor Fernando Torres, but just in case any doubts remained about their new striker's pedigree, they were emphatically dismissed against Swansea.
Trailing to a Terry own goal after 11 minutes, Costa set about Swansea like a one-man wrecking ball, powering home a header on the stroke of halftime, converting a Cesc Fabregas cross after the restart and then guiding a Ramires shot home.
Remy swept the ball into the net unmarked on the edge of the area to make it 4-1, having only been on the pitch a matter of minutes to add a touch of gloss to the result.
Shelvey grabbed a late consolation of little significance, except perhaps to Chelsea manager Jose Mourinho who values a water-tight defence and will not be impressed by his team conceding a fifth goal in two games after their 6-3 win at Everton two weeks ago.
Arsenal handed a debut to striker Danny Welbeck, who had an early chance to score when he raced on to a misplaced pass from David Silva and attempted an audacious chip over keeper Joe Hart which struck the inside of the post.
If the former Manchester United forward wanted a lesson in ruthlessness, it was provided by others on the pitch.City's Aguero opened the scoring with a tidy sidefoot, Wilshere levelled in the second half with a beautiful run into the box and dinked finish and, not to be out-done, close-season signing Sanchez let fly with a perfectly-timed sidefoot volley.
"I am satisfied because I thought this year it would be very difficult for us to defend our title," said City manager Manuel Pellegrini, before lambasting referee Mark Clattenburg for his performance.
Newcastle's woes intensified as they were left at the foot of the fledgling standings following a humiliating 4-0 defeat at Southampton that heaped pressure on manager Alan Pardew.
Graziano Pelle scored twice inside 19 minutes, Jack Cork added another after the break and Morgan Schneiderlin capped an impressive Southampton performance with a goal at the death.
Tottenham led going into the final eight minutes against Sunderland before a Harry Kane own goal gave the home side their third draw in their opening four games, leaving the London club level with Manchester City on seven points.
Everton striker Romelu Lukaku scored against his former club West Brom after two minutes while Kevin Mirallas made the game safe with a shot that squirmed under goalkeeper Ben Foster midway through the second half.