Manchester - Arsene Wenger accepted leaders Manchester City would be "hard to stop" in their quest for the Premier League title especially if they continued to get the rub of the green from referees.
The Gunners manager accused City forward Raheem Sterling of diving after he won a penalty in his team's 3-1 victory over Arsenal at the Etihad on Sunday.
Veteran French boss Wenger was furious with the performance of referee Michael Oliver who awarded the spot kick and a dubious goal, which the Arsenal manager claimed was offside.
"I believe it was no penalty," said Wenger. "We know that Raheem Sterling dives well, he does that very well.
"And the third goal was offside. I am very upset because at 2-1 we were in the game. The third goal was the killer and it is by coincidence that mistakes always go for the home team, as we know.
"It is unfortunate that the game finished the way it finished. I am disappointed. You can accept if it City win in a normal way, they are a good side but this is unacceptable," added Wenger after a match that left his side 12 points behind the table-toppers.
"Last season we lost two offside goals and it has happened again. City will be hard to stop."
'Never say never'
City have 10 wins and a draw from their opening 11 league games this season, prompting speculation they could emulate Wenger's 'Invincibles' Arsenal team that were through the whole of the 2003/04 campaign without losing a Premier League fixture.
"Look, can anyone stop them?" asked Wenger rhetorically. "It will be difficult this season with the way they have started, the way they are on a run, they quality they have.
"They will be difficult to stop but you never say never. If, on top of that, they have decisions like that at home, they will be unstoppable."
Wenger had grounds for complaint when Laurent Koscielny was judged to have brought down Sterling for Sergio Aguero to make it 2-0 from the penalty spot and television replays suggested he was especially hard done by as David Silva appeared offside before setting up Gabriel Jesus for City's third goal in the 74th minute.
"I felt it was an intense game of quality for both sides," said Wenger. "Man City are on a high but I felt we had plenty of dangerous situations and chances.
"Overall, once again, the referee made the decision again, with a penalty and an offside goal. We are used to it when we come here. I feel they (referees) don't work enough, because it happens every season. It is unacceptable," he insisted.
Kevin De Bruyne gave City the lead while, trailing 2-0, Arsenal were briefly given hope when substitute Alexandre Lacazette pulled a goal back.
City manager Pep Guardiola was understandably delighted to have beaten a title rival so emphatically.
After winning just two games against the top six clubs last season, City have already won all three in the current campaign, hammering Liverpool and outplaying champions Chelsea and, now, Arsenal.
"All I know is everybody can beat us, that is a principle in all sports," said Guardiola. "It doesn't matter what happens in the past. You can win the Champions League and lose the day after.
"Last season we were only able to win twice against the big teams, at Old Trafford against United and here against Arsenal. This season in November, we already won three times, one more."
The Spaniard added: "We spoke about that. If you want to win the Premier League, you have to win, especially at home, against Liverpool, United, Arsenal, Tottenham, Chelsea. It is so hard to win away."