Lucas Torreira has been praised for reigniting Arsenal's dirty streak on the eve of Sunday's north London derby.

Torreira has played a starring role for Arsenal as they head into a mouth-watering fixture against Tottenham off the back of an 18-match unbeaten run.

The Uruguay international, 22, has added some much-needed bite to Arsenal's midfield following his summer arrival from Sampdoria.

And Emmanuel Petit, the former Gunners midfielder whose combative partnership with Patrick Vieira spearheaded Arsenal to the league and FA Cup double in Arsene Wenger's first full season in charge 20 years ago, believes Torreira has been Arsenal's missing link in recent seasons.

"In terms of fighting spirit, Arsenal have needed a player like Torreira," Petit told Press Association Sport.

"With the old back four that I played with and during the Invincibles' era, we had players with anger who would fight for every ball.

"Arsenal have been too glamorous in the past few years, and not dirty enough, but with Torreira, the dirt is coming back into the team.

"He is not the most talented player, but he is like a dog on the pitch, he is a leader and sets an example.

"He doesn't impress you physically, but you can feel his breath on your neck, and his foot in your calf because he is there all the time, and that is the kind of player you need in a team."

Unai Emery will get his first taste of the north London derby when Spurs travel to the Emirates Stadium. The Spaniard endured a testing start to his tenure following successive league defeats against Manchester City and Chelsea.

But since those early setbacks, Emery has overseen Arsenal's most resilient run in recent years, overseeing progression to the latter stages of the Europa League, while also being on the brink of the top four.

A win for Arsenal on Sunday would take them above Tottenham ahead of a visit to Manchester United on Wednesday.

"There was a routine in the dressing room under Arsene, but routine is the worst thing a player and manager can expect," added Petit.

"Unai Emery has arrived and changed every detail and that has helped. It's refreshing for the players to have that new energy and we have seen the results straight away.

"This game is a big test for Arsenal, and although they can forget about winning the Premier League title because collectively and individually Manchester City and Liverpool have better sides, there is no doubt they can qualify for the Champions League."

::Emmanuel Petit is a Paddy Power ambassador. Read more of his thoughts at news.paddypower.com