Champions Manchester United beat Premier League leaders Arsenal 1-0 at Old Trafford on Sunday with Robin van Persie once again tormenting his former team mates with a soaring first half header.
The result left Arsenal on 25 points from 11 matches, two clear of Liverpool, with United moving ominously up to fifth on 20 ahead of local rivals Manchester City, who were stunned 1-0 at struggling Sunderland and drop to eighth on 19 points.
The day's big match was a litmus test for both sides, with the North Londoners arriving as the form team eager to end years of hurt at United and charge 11 points clear of their old rivals who are under new management.
Alex Ferguson may have been watching from the stands rather than shouting from the bench but David Moyes' side ensured the outcome remained depressingly familiar for the Gunners, who have now won only one of their last 10 league encounters with United.
It was Arsenal's first away defeat since March after a run of 15 games unbeaten in all competitions and thrust United right back into the title race after a faltering start to the campaign.
Van Persie bagged his seventh league goal of the season when the Dutchman rose to meet a Wayne Rooney corner kick and head home at the far post in the 27th minute.
Arsenal failed to live up to expectations, creating few chances on a strangely muted evening for their record signing Mesut Ozil, and could even have found themselves 2-0 behind after an hour when Rooney shot just wide.
In the earlier game, Gus Poyet's struggling Sunderland jolted the Premier League with an electrifying 1-0 win over big-spending Manchester City at the Stadium of Light.
On a great afternoon for the reviving giants of north-east football, local rivals Newcastle United won by the same scoreline at Tottenham Hotspur to move into the top half of the league.
Sunderland, second from bottom with just four points from 10 games before Sunday, chalked up a fourth successive 1-0 home win over City thanks to a 21st-minute goal slotted in by Phil Bardsley from the left side of the box.
With Uruguayan manager Poyet pacing around on the touchline as Sunderland faced a late City barrage, the Black Cats held on for their first clean sheet in 15 matches and a stunning win over a side who hammered Norwich City 7-0 last weekend.
Newcastle United goalkeeper Tim Krul performed the heroics with 14 saves at White Hart Lane to deny Tottenham a chance to move level with Liverpool.
The focus was on both goalkeepers from the start, with Hugo Lloris left out of the Tottenham squad on medical advice after the French international had been knocked unconscious at Everton last week.
The 42-year-old Brad Friedel had to make a couple of saves early on but was powerless to prevent the livewire Loic Remy firing Newcastle in front after 13 minutes on a crisp but sunny afternoon.
The Frenchman picked up a beautifully-measured pass from Yoan Gouffran to beat the offside trap, dart around the goalkeeper and stab home for his seventh league goal of the season.
Shola Ameobi could have made it 2-0 when he had the ball in the net after 38 minutes but was ruled offside while Krul had earlier made a flying save to keep out a goal-bound Roberto Soldado header.
Krul said that first crucial save was probably the best, with the sun low in the sky and making it hard to see clearly.
Image: Robin Van Persie
Photograph: Phil Noble/Reuters