West Ham's move to the former Olympic Stadium has been beset by controversy and Wednesday night's EFL Cup clash with Chelsea saw violence erupt.
Here Press Association Sport answers some of the questions relating to the Hammers' move from Upton Park.
Why did they move?
West Ham moved to the former Olympic Stadium to boost their profile. "Our trajectory is admired across the world," vice-chairman Karren Brady said earlier this month. The Hammers' move from Upton Park, their home since 1904, to the £701 million London Stadium, can be traced back to the Olympic bid and the squabbling over what to do with the arena built for London 2012 once the Olympics and Paralympics had closed. Many argued a football tenant was the only possible solution. And West Ham successfully negotiated an annual rent of £2.5m on a 99-year lease from the London Legacy Development Coporation, the publicly funded authority which owns the stadium and disclosed the deal in April. LLDC must provide the goalposts and corner flags and is responsible for costs associated with maintenance, policing, cleaning and pest control at the 60,000-seat arena. The deal was described as "ludicrously generous" by the Taxpayers' Alliance. The club can also claim the lion's share of any naming rights deal.
What do the supporters think of the move?
West Ham played 2,398 matches over 112 years at Upton Park, also known as the Boleyn Ground, before departing with mixed emotions. Leaving their spiritual home - and home for World Cup winners Bobby Moore, Geoff Hurst and Martin Peters - was heart-wrenching for many who bemoan the loss of 'traditional' football stadia. Once within an outstretched arm of the touchline, now the supporters are further away. Many fans have said football should not be played in stadia with athletics tracks, insisting the atmosphere is lost. There is a retractable section of seating which brings fans closer to the action at the former Olympic Stadium. And at the venue's first capital derby the atmosphere was largely good, with the majority enjoying an excellent game. The main challenge for the atmosphere was the booming public address system. Nine competitive games in, the Hammers now have five wins.
What factors have led to the trouble?
There had already been disturbances in the stands and outside the ground at some of West Ham's previous home matches, and a series of measures were put in place ahead of a first London derby. Four people were arrested following disorder at the October 1 Premier League match against Middlesbrough. The defeat by Watford on September 10 saw clashes in the stands. There were reports of infighting between West Ham supporters, with some frustrated at persistent standing. Supporters were given the option to switch the location of their season tickets. The numerous transport options available to get to Stratford make segregation outside of the ground a challenge, while it was tested inside the stadium on Wednesday night as rivals taunted each other. The capacity of the 60,000-seat arena has been capped at 57,000 for football fixtures and 45,957 were in attendance, along with a heavy police presence. Chelsea sold out their allocation of 5,182 tickets.
What punishment could be imposed on the clubs now?
The fact West Ham and Chelsea issued prompt statements of condemnation and vowed to use CCTV to identify troublemakers means they may escape sanctions. Fines, ground closures and partial closures are options available to the Football Association, if clubs are proven to be negligent in such incidents. However, both clubs made appeals to their supporters in attempts to guard against the potential for trouble in the build up to the match. The FA's strategy over such matters is education and improvement, rather than disciplinary action.