Arsenal manager Arsene Wenger fears referees have gone soft on flying elbows as he reveals Hector Bellerin didn't know what the score was after 'dangerous' Marcos Alonso challenge

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Arsene Wenger accused referees of going soft on football's flying arms and elbows after Arsenal's defeat at Chelsea was triggered by Marcos Alonso's controversial goal.

As Alonso climbed to head the opener in a 3-1 victory for the Premier League leaders he smashed Hector Bellerin in the face with an arm and left him concussed.

Bellerin was dazed, did not even know the score when the medics dashed on to provide treatment and was unable to continue. 

Arsenal were forced to substitute Hector Bellerin after he suffered mild concussion

Referee Martin Atkinson, however, saw no reason to rule out the goal and Eden Hazard and Cesc Fabregas stretched Chelsea's lead before Olivier Giroud pulled one back in stoppage-time.

'It was 100 per cent a foul,' said Wenger, when asked about the 13th-minute opener. 'It was even dangerous play. Bellerin was concussed. Not completely knocked out. He didn't know the score at the time. He didn't see the goal.

'One of the peculiarities of the game today is that referees are much more severe with tackles on the ground and let much more go with elbows in the face.

'It's not only today, but in many, many games I see that. But it's more dangerous to hit the head than the legs.' 

In real-time, it appeared to be a robust and athletic challenge for the ball by Alonso, using his arms for leverage with the benefit of a running leap on Bellerin, who was forced into what was virtually a standing jump. 

Marcos Alonso beat Bellerin to the ball in the air to give Chelsea the lead after 13 minutes

Alonso celebrates after giving Chelsea the lead but he leaves Bellerin on the floor

Graeme Souness, on Sky Sports, thought it was a good header by the Chelsea wing- back with 'eyes only for the ball' and former referee Dermot Gallagher agreed, saying it was 'fair' because he had not 'led with the arm'.

Chelsea boss Antonio Conte said: 'In England, in this league, this is always goal. 

'In Italy, maybe, maybe, yes a foul and we can have a conversation. Here I don't think it's right to talk about it.

'Alonso jumped more than Bellerin and scored a goal. 

'For me this is a correct decision. We can see this situation a lot in England and it's normal.'

Slow-motion TV footage and freeze-frames made the challenge seem worse than it did to the human eye, with Bellerin's head jolted back by the force of the arm in his face.

Less than a fortnight ago, Hull midfielder Ryan Mason suffered a fractured skull in a clash of heads with Gary Cahill, at the same end of Stamford Bridge and no chances were taken with Bellerin, who was taken off to watch the second half from the bench.

Arsenal's club doctor is Gary O'Driscoll, who has staunch views on concussion, having left his role with the Irish rugby union and rejected a job with the British Lions based on a disagreement over treatment of head injuries.

He is the son of Barry O'Driscoll, the former World Rugby medical adviser and a former Ireland rugby international who has been a leading campaigner for greater care to be taken with concussion victims in rugby. 

As chair of the Premier League doctors' group, Gary drove changes in protocol to ensure an independent doctor would be present at all games to give a final verdict on suspected cases of concussion. 

Arsenal physio Colin Lewin treats Bellerin after the clash before deciding to withdraw him

Television replays showed just how hard Alonso struck Bellerin's face with his elbow

Although Bellerin remained conscious, he is believed to have suffered mild concussion

'The decision was for me very quick,' said Wenger. 'You have to respect that. It's the head.

'We were 1-0 down and after that it is much more difficult. Chelsea are very strong at defending and very good on transition and counter-attack. And we paid for that.

'If you look at the goals, it's all that. We lost many balls in positions where you cannot afford to lose it when you play against a team good on counter-attack. 

'Our keeper had not a lot to save even if I conceded we did not create enough in the final third. It was the kind of game Chelsea love and they mastered very well.'

Hazard beat several Arsenal players on a mesmerising run before firing past Petr Cech 

Hazard put the tie beyond the Gunners by scoring at a time when Arsenal were threatening 

Having lost at home to Watford on Tuesday, this was Arsenal's second defeat in five days and they are a dozen points adrift of Chelsea with 14 Premier League games to play.

'Chelsea look at the moment in full confidence, powerful and strong,' said Wenger.

'It is for them to lose it. They are in the best position and they don't play in Europe. They can wait every week for the next game and prepare properly.

'Where does that leave us? To focus and prepare to win the next game. That's what football is about.'

Stamford Bridge stewards order fans to sit down and stop taking pictures of the Arsenal boss