|Nicklas Bendtner gets a yellow card as Arsenal collect three valuable points [GALLO/GETTY]
Abou Diaby was the hero at the Emirates Stadium when his 72nd minute header revived Arsenal's hopes of playing a major role in the English Premier League title race with a 1-0 victory over rivals Liverpool.
Arsene Wenger's side had collected just one point from their previous three games but their crucial home win ensured they maintained the pressure on Chelsea and Manchester United who both missed out on vital points.
Chelsea crashed to a 2-1 loss at Everton and saw their league lead trimmed to a point by Manchester United, who drew 1-1 with Aston Villa.
A brilliant Louis Saha missed a penalty but still scored twice for Everton after Florent Malouda put Chelsea ahead, with the French striker's goals doing a big favour for former club United, who survived Nani's sending off to earn the point at Villa.
Defeat for Liverpool ended their seven game unbeaten run and they now sit fourth, level on points with fifth-placed Manchester City but having played two games more.
"We believe in our title chances and you could see that Chelsea again lost tonight and Manchester United dropped points, it is still open,'' Arsenal manager Arsene Wenger said.
"I don't see any mathematical reason why we shouldn't believe.''
Arsenal created the better first half opportunities and should have been ahead after just seven minutes when the unmarked William Gallas headed over from Fabregas's free-kick.
Fabregas burst forward to collect a neat back heel from Nicklas Bendtner and was brought down by Liverpool defender Martin Skrtel on the edge of the visitors' box.
The free-kick was wasted, but the move appeared to show Arsenal the way through the Reds back-line.
In the second half Andrey Arshavin served early notice of Arsenal's more positive approach when he fired a firm shot into the side netting from a tight angle.
Liverpool responded in kind, carving out a good chance for the advancing Lucas that ended with the young Brazilian mirroring Bendtner's miss of the first half.
Moments later Gallas produced an outstanding last-ditch tackle to deny David Ngog who had been sent clear from the halfway line by Steven Gerrard's pass and the balance of the clash appeared to have shifted in the visitors' favour.
Arsenal then dominated the crucial period of the game that culminated in Diaby's goal.
Tomas Rosicky should have done much better when he found himself bearing down on Liverpool keeper Pepe Reina and Bendtner was unlucky to see Daniel Agger hack his goalbound shot to safety.
Bendtner played the ball wide to Rosicky who delivered the perfect cross for Diaby to head home from six yards out.
At Goodison Park, Chelsea were in control when Malouda scored after 17 minutes by latching onto Didier Drogba's header from goalkeeper Petr Cech's long clearance.
But Louis Saha exposed Chelsea's weakness from set pieces by heading in a 33rd-minute equaliser from Landon Donovan's cross, which dropped over Frank Lampard.
Donovan won a penalty before half time after being clipped in the area by Ricardo Carvalho, but Saha's spotkick was saved by Cech.
But Saha found the net again in the 75th after connecting with a long ball that was misjudged by Chelsea captain John Terry.
United had Nani sent off for a two-footed challenge on home captain Stiliyan Petrov.
The Portugal winger, who has recently been in the best form of his Old Trafford career, is now set to receive a three-match ban that will also rule him out of the February 28 League Cup final against Villa.
The score was already 1-1 when Nani saw red in the 29th minute.
Carlos Cuellar had headed Villa ahead after latching onto Stewart Downing's ball, but United for the 10th time this season benefited from an own goal.
West Ham and Wolverhampton moved out of the relegation zone with victories and are level on 24 points, one above the drop zone. Hull are also on 24 after losing 1-0 at Blackburn.
Alessandro Diamanti and Carlton Cole scored the goals as West Ham enjoyed a 2-0 victory over Birmingham.
At Wolves, midfielder David Jones netted his first league goal of the season to clinch a 1-0 victory over sixth-place Tottenham.