If Arsenal are top of the table despite another demonstration of defensive ineptitude, the Premier League may well be succumbing to a form of "leadership by the worst".

It is difficult to remember when the title has ever been won by a team with a defence as ramshackle as Arsenal's again showed itself to be, at least in the continued absence of Thomas Vermaelen, but the flip side of that is that if Arsène Wenger's team do triumph this season it will be because of sumptuous forward play, exemplified here by two superb goals from Samir Nasri, who must surely be the Premier League's player of the season so far.

Nasri has now struck eight league goals in this campaign and created many more. Whisper it, but he may even be starting to fulfil the "new Zidane" prophesies that proliferated when he was a youngster in Marseille. "He was the difference between the sides," the Fulham manager, Mark Hughes, said after this latest Nasri exhibition at the Emirates.

Nasri did not foil Fulham entirely by himself. Andrey Arshavin was also influential. Arshavin, indeed, could have opened the scoring in the sixth minute but his close-range volley was blocked by Mark Schwarzer. Then in the 12th minute Arshavin darted through midfield and fed Nasri, who poked wide from 15 yards. Two minutes later the Frenchman atoned for that miss. After again being teed up by Arshavin, Nasri sidestepped two Fulham defenders and rammed the ball into the roof of the net from eight yards.

The snow had melted in London but Arsenal were threatening an avalanche of goals. Arshavin and Marouane Chamakh both went close and Nasri was tormenting the left-back Matthew Briggs so much that Hughes withdrew the 19-year-old after 28 minutes. "It was a bit too much for him," Hughes explained. Within three minutes, however, Arsenal showcased their own defensive confusion and allowed Fulham to snatch an equaliser from their first real attack.

Sébastien Squillaci and Laurent Koscielny clashed heads while jumping for the same ball at the edge of the area and while the latter lay injured on the ground, Clint Dempsey clipped a pass through to the suddenly unmarked Diomansy Kamara, who finished well from 14 yards.

This fresh evidence of Arsenal's defensive vulnerability emboldened Fulham and spread familiar jitters through Wenger's team. Moments before half-time Kamara should have put Fulham in front but, after the Arsenal defence was prised apart by a routine ball through the middle, Lukasz Fabianski saved well.

Arsenal began the second half strongly and the trickery and penetrative running of Arshavin and Nasri returned to the fore. In the 57th minute the pair combined anew but, after feints from the Russian left two defenders on their backsides, his low shot was saved by Schwarzer.

Still Arsenal remained ropey at the back, as Dickson Etuhu proved on the hour when he rose unchallenged to meet a corner. Fortunately for the home side his connection was poor. Wenger introduced Robin van Persie for Tomas Rosicky with half an hour to go but the Dutchman's first significant contribution was not in attack – in the 70th minute he had to clear off the line as another Fulham corner sent Arsenal into a panic.

Five minutes later, though, Van Persie was in action at the other end, laying the ball off for Nasri to score his wonderful winner. Nasri collected the ball at the edge of the Fulham box and displayed Zidane-esque balance to glide past two defenders and Schwarzer before swivelling and shooting into the net from an awkward angle.

"His goals were a combination of touch, intelligence, special talent and also calmness because he needed to be patient to finish on both occasions," gushed Wenger, claiming vindication for having signed him for a fee of £11m or more two seasons ago. "Many people questioned me when I took him here but he is showing he is a special talent and I think there is more to come from him."

Although Chamakh came close to a third for Arsenal, the home team's fragility at the back meant Fulham had further chances to equalise, notably in the 78th minute when Etuhu stabbed wide after another scramble in the box. "I agree that at stages we looked a bit vulnerable in the air," said Wenger.

"But every team is struggling for consistency at the moment. We have the desire and spirit to fight for the title – are we good enough? We will find out."