Arsene Wenger has urged referees to stop allowing "bad habits" to creep back into the game after a weekend of controversy on the pitch.

Bolton will today receive an apology from Rob Styles after he wrongly awarded Manchester United a penalty in their 2-0 win on Saturday.

Jlloyd Samuel was adjudged to have fouled Cristiano Ronaldo when replays clearly showed he won the ball. It proved a decisive moment in the match as the Portuguese winger scored from the spot to open the scoring.

There was more furore yesterday when Wigan were awarded another penalty in their 2-1 win over Manchester City after Wilson Palacios theatrically fell to the floor following a challenge from Javier Garrido.

Wenger does feel that the Football Association's Respect campaign has worked, with less flash points between players and officials, yet the Arsenal boss is worried about the number of mistakes being made.

He said: "There has been a lot of coverage of the FA's Respect' campaign towards referees and I believe that, up to this point, it has worked.

"It's down to the referees not to let bad habits come in again, but so far it has had positive effects."

The Arsenal boss warned the biggest test for referees is yet to arrive — he expects that will come when the trophies are decided towards the end of the season.

He said: "You see fewer players around the referee especially, but perhaps you have to wait a bit longer because at the start of the season the players, managers and fans of the clubs are under less pressure.

"The real test will be between February and May — you have to make slow progress and I believe that a little has been made up to now."