London: Arsenal manager Arsene Wenger voiced concern about midfielder Granit Xhaka's disciplinary record, ahead of Sunday's north London derby clash with Tottenham Hotspur.
Xhaka, 24, has been sent off eight times for club and country since April 2014 and has just completed a domestic suspension for a red card in last month's 3-2 victory over Swansea City.
With Santi Cazorla expected to be sidelined by an Achilles injury, Xhaka is in line to face Spurs and Wenger is hopeful the Switzerland midfielder will keep a lid on his aggression.
"Am I a bit concerned? Yes, of course," Wenger told his pre-match press conference on Thursday. "The discipline is important and we want to be effective in all situations we face.
"In the derby it is important to keep control of your reaction and to have a strong discipline because it is part of the effectiveness in these games.
"Normally he is a very composed and calm guy. Sometimes on the field he has a reaction that is a bit impulsive and he knows that.
"He has to work on that and keep control of his reactions in the game."
Xhaka scored as Arsenal came from 2-0 down to win 3-2 at Bulgarian side Ludogorets on Tuesday, securing their place in the Champions League last 16 for the 17th season running.
As well as Cazorla, Wenger also has fitness concerns over Theo Walcott, Hector Bellerin and Nacho Monreal, all of whom missed the game in Bulgaria.
Left-back Kieran Gibbs could also miss out after injuring his shoulder against Ludogorets, while striker Lucas Perez has been ruled out for around a month with an ankle problem.
Arsenal have lost just one of the last eight north London derbies, but have not beaten Spurs at home in the Premier League for three years.
Wenger's side go into the weekend second in the table, below leaders Manchester City on goal difference and three points above fifth-place Spurs.
But with Spurs the last unbeaten team in the table, Wenger is expecting a tight contest.
"It is an interesting clash. For us it is a very important game because we are in a strong position in the league that we want to strengthen," he said.
"Overall Tottenham as well, so it is very tight at the top of the league. We are more focused that it is a home game, to win the game -- whether it is Tottenham or somebody else.
"We want to win our home games because our position in the league is very important and we go into a period where we play big games and we want to win the big games."