The London Stadium's first major test collapsed into near-chaos. West Ham's 2-1 win over Chelsea in the EFL Cup on Wednesday night saw Slaven Bilic's team put in their best performance at their new home and yet the club was left defending a night of ugly crowd scenes -- with seven arrests made so far and a Football Association investigation launched.
Without the outbreak of violence that took place in the Sir Trevor Brooking Stand as Chelsea fans made for the exit just before full-time, the evening might well have been depicted as one of mere teething troubles, from which lessons might be learned. That disturbing flashpoint, though, in which two sets of fans surged at each other through a weakness in the segregation between them, has called the safety of attending the stadium into serious question.
Police and stewards did just about enough to prevent an all-out riot but a hail of coins and the sight of ripped-out seats flying through the air made it more than just a standoff.
Chelsea fans' initial allocation of 6,000 tickets had been reduced to 5,000, with their access reduced to eight turnstiles. And yet once the game was underway, the London Stadium crackled with atmosphere with goals from Cheikhou Kouyate and Edimilson Fernandes bringing back the noise levels fans once generated at Upton Park.
The night air still seethed with the menace that could often be felt back at the old place. Upton Park regrettably signed off in May with Manchester United's team coach showered with missiles, and the same element clearly still makes its way to the London Stadium.
Throughout the second half, as a home victory became likely, the goading was ramped up across a segregation area amounting to little more than an oversized piece of tarpaulin. And the structure of the concourse inside the stadium, which gives free movement of home fans around to all but the away area, allowed agitators to pile into an area they did not have tickets for.
"You could see it building," Hammers fan Nigel Kahn, previously on a fans' steering committee for the new stadium, told ESPN FC. "They were starting to wander to that back section."
The tension eventually boiled over into scenes which filled the back and front pages of UK newspapers. "It's indiscriminate, throwing seats," said Kahn. "That could hit a kid."
In postmatch from the vantage point of the upper stand, there was the unnerving sight of neon-clad response teams charging into the gloom to calm skirmishes. Served by nine transport connections, and despite heavy controls on Chelsea fans' transit, the vast expanse of Olympic Park and the industrial estates that surround the stadium requires a huge, concerted policing operation to lock down the area for potential tinderbox fixtures.
Problems had been widely feared and planned for as soon as the EFL Cup draw paired West Ham and Chelsea together on Sep. 21, with consultations carried out with the Football Supporters' Federation (FSF). A carefully managed ticket policy contributed, to a low gate of 46,000 (11,000 below capacity). That and the efforts of West Ham, stadium management company LS185 and London's Metropolitan Police Football Unit could not prevent Bilic reluctantly having to talk about something other than his team's best football of the campaign.
"Ask me one more question about the game, anything," he said in vain afterwards.
"We must stress that the overwhelming majority of supporters who have visited London Stadium have supported the team exceptionally and behaved impeccably," read a West Ham statement.
The stadium had suffered previous difficulties, with fights breaking out between fans and stewards in the ground during a 4-2 loss to Watford on Sept. 10, and then outside the ground between rival fans on Oct. 1, after a 1-1 draw with Middlesbrough.
The stewarding, as organised by LS185 rather than the club, uses different, minimum-wage employees to those at Upton Park, and getting to and from the ground is served by only intermittent signage, as well as low-level lighting. Those walking back to transport connections at night do so in near-darkness.
Wednesday was the starkest reminder yet that the new stadium was not constructed with football in mind. The area where the flashpoint took place was near trackside at the London 2012 Olympics; back then athletics fans happily circulated without the tribalism of football supporters.
"Myself and our chief exec were there last night observing proceedings," FSF caseworker Amanda Jacks told ESPN FC. "We are going to compile a report and the Chelsea supporters' trust will do likewise, and we encourage fans to get in touch.
"We will take feedback to the various stakeholders so we are part of the solution. It's important they listen to it from a supporters' perspective. Fans can tell them plenty about what went wrong."
Football stadiums require more stringent security than the London Stadium and its staffing proved able to offer on Wednesday. In the aftermath, Chelsea officials expressed sympathy for the problems West Ham face at their new home, while condemning the behaviour of those who involved themselves.
Stamford Bridge, due to be rebuilt from next summer, will surely be designed to make sure such confrontations are not made so possible, as has been practice for decades in English football grounds.
"I sat above the away fans at Upton Park for 10 years and I never saw anything like that apart from when [London rivals] Millwall came," said Kahn.
West Ham have significant issues to confront before their new stadium becomes a respectable and safe stage for big-match football.