LONDON - Arsenal manager Arsene Wenger compared Abou Diaby to former midfield general Patrick Vieira on Saturday after the Frenchman scored twice in a 4-1 home defeat of Portsmouth which sent the Gunners top of the Premier League. The imposing Diaby thumped Arsenal in front after 18 minutes and side-footed a second goal three minutes later to put a rampant Arsenal side in control. Since joining Arsenal as a 19-year-old in 2006, Paris-born Diaby has shown glimpses of his all-round midfield game but injuries, particularly a broken and dislocated ankle soon after arriving in north London, have held back his progress. Arsenal were linked with a move for Vieira recently, but Diaby looks purpose-built to emulate the former skipper who has never hit the same heights at Inter Milan as he did at Arsenal where he led the side unbeaten to the title in 2003-04. "I think Diaby is a bit more offensive than Patrick Vieira but when he plays a more defensive role he is very similar," Wenger told reporters. "His ability to win the ball back is just like Vieira. He is capable of a very quick transitions from defence to attack and has fantastic strength box to box - nobody can go with him. "He has had a lot of injuries, and was out for nine months two seasons ago (2006-07). He worked very hard in the summer and this could be his season. "He has prepared very well, looks sharp and strong and has everything for a Premier League midfielder." Arsenal were irresistible against Portsmouth before the break with Cesc Fabregas masterminding everything from midfield but the Spaniard failed to reappear after the break. "He has a hamstring problem and may be a bit short for Wednesday," Wenger said of his chances of playing in the second leg of their Champions League playoff against Celtic, although with a 2-0 lead from the first leg he was not unduly worried. Wenger said Arsenal's impressive start to the season should help rekindle the atmosphere at the Emirates Stadium where a mood of doom and gloom descended after last season's faltering start in the Premier League. "We are trying to create something special at the club, to make it more warm," Wenger said, referring to handing out of 60,000 red and white scarves before the start. "Up north the fans are bit more fanatic but in a big city like London the players have to get the people out of their seats and not the other way round. "Last year maybe the vibe wasn't quite right. We never gave enough belief to the fans and maybe the fans were affected by the whole negative publicity."