The Magpies have already had two men sent off in a mixed start to the season.
Newcastle ‘keeper Tim Krul has called the the team’s disciplinary record unacceptable and insisted they must improve rapidly if they are to give themselves a chance this season.
"We know it's not acceptable and we have to learn quickly," said the Ductchman, in an interview with BBC Sport.
"It's hard enough with 11 players in the Premier League and to get two first-half sendings off makes it hard for us.”
Newcastle have seen two players sent off in their first four Premier League games and have yet to secure their first win.
Daryl Janmaat was shown two soft yellow cards in the Magpies defeat to Swansea, while Aleksandar Mitrovic received a straight red for a high tackle on Arsenal’s Francis Coquelin.
Despite their mixed results, signs have been encouraging on Tyneside and Krul believes the side are heading in the right direction, adding:
"We have to look at the positives, we've got a great group and spirit, real quality and we just have to get the first win."
Steve McClaren set about creating a competitive squad this summer after Newcastle’s woeful showing last season, and looks to have done just that.
His team’s battling display in the goalless draw at Old Trafford suggested a togetherness and team spirit which should stand them in good stead for the season.