An Arsenal supporter was arrested at the Emirates Stadium on Saturday after red wine was thrown at the Manchester United bench. The flashpoint took place as United celebrated the opening goal of their 2-1 win and led to an angry exchange between some of the club’s substitutes and fans in the seats behind them.

Arsenal moved to identify the culprit, calling on the stewards in attendance and the CCTV footage, and they have promised to liaise with the Metropolitan Police and ban any individual whose guilt is proven. The club take a hard line against antisocial behaviour. The wine splashed some of the United personnel who were understandably not happy. It is unclear whether United will make an official complaint but they are keen that the matter be resolved.

There has long been the feeling at United that their staff and substitutes lack proper protection at the Emirates as the visiting dugout seats are out in the open.

Sir Alex Ferguson, the club’s former manager, complained in 2008 about the abuse that he received from supporters close to him, describing it as “nasty”. “It is too open for my liking,” he once said. “It should not happen when you build a modern stadium. You need tin helmets. It is a weakness in the planning that you don’t provide safety for the visiting substitutes and staff.”

Passions ran high on Saturday and after Wayne Rooney had scored United’s second goal in the 85th minute, the Arsenal fans that want to see the manager, Arsène Wenger, sacked, could be heard. One of them held aloft a small, A4-sized placard, which read: “Enough is enough. Wenger out.” A steward quickly moved in to confiscate it. The club have a policy to remove such items on safety grounds because they risk sparking argument among fans.

Arsenal face an anxious wait to see whether Jack Wilshere faces a lay-off on disciplinary or fitness grounds. The Football Association will study the footage of the moment when the midfielder pushed his forehead up towards Marouane Fellaini in the 30th minute. The referee, Mike Dean, took no action at the time.

Wilshere was forced off early in the second half after rolling his left ankle following a challenge from the United defender Paddy McNair. An x-ray after the game was clear but there is the fear of soft tissue damage.

Wenger said Wilshere had very little chance of being fit for Wednesday’s Champions League tie at home to Borussia Dortmund. The goalkeeper, Wojciech Szczesny, who came off with hip trouble after colliding with Kieran Gibbs before United’s first goal, was not too badly injured, according to Wenger.