It's high stakes for UK companies as sports wagering starts to spread out in America.

From Tuesday, new guidelines on wagering came into impact in Delaware, a tiny east coast state about 2 hours from Washington.

Neighbouring New Jersey could start accepting sports bets as early as Friday.

The changes are the very first in what might end up being a wave of legalisation after the Supreme Court last month cleared the method for states to permit sports betting.

The industry sees a "once in a generation" opportunity to establish a brand-new market in sports-mad America, stated Dublin-based monetary analyst David Jennings, who heads leisure research at Davy.

For UK firms, which are grappling with consolidation, increased online competition and tougher guidelines from UK regulators, the timing is particularly opportune.

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But the market says counting on the US stays a risky bet, as UK companies deal with complicated state-by-state guideline and competition from entrenched local interests.

"It's something that we're really focusing on, however equally we don't wish to overhype it," said James Midmer, spokesman at Paddy Power Betfair, which just recently bought the US dream sports website FanDuel.

'Take some time'

The US represented about 23% of the world's $244bn (₤ 182bn) in gaming earnings in 2015, according to a report by Technavio, external published in January.

Firms are wanting to take advantage of more of that activity after last month's choice, which overruled a 1992 federal law that disallowed states outside of Nevada and a few others from authorising sports wagering.

The ruling found the law was an over-reach of federal power. But the court it did not in fact legalise sports betting, leaving that concern to local lawmakers.

That is expected to lead to substantial variation in how companies get licensed, where sports wagering can happen, and which events are open to speculation - with huge ramifications for the size of the market.

Potential revenue varieties from $4.2 bn to almost $20bn each year depending on aspects like how many states transfer to legalise, Oxford Economics estimated in a 2017 study for the American Gaming Association.

"There was a great deal of 'this is going to be big'", stated Will Hawkley, London-based head of leisure for consultants KPMG.

Now, he said: "I believe the majority of people ... are looking at this as, 'it's an opportunity however it's not going to be $20bn and it's going to be state by state and it's going to take time'."

'Remains to be seen"

Chris Grove, handling director at Eilers & Krejcik Gaming, forecasts that 32 states will legalise sports betting in some kind by 2023, creating a market with about $6bn in annual profits.

But bookmakers deal with a far different landscape in America than they carry out in the UK, where wagering shops are a frequent sight.

US laws minimal gambling mainly to Native American lands and Nevada's Las Vegas strip up until fairly recently.

In the popular imagination, sports betting has long been connected to a 1919 baseball World Series match-fixing scandal.

States have actually also been sluggish to legalise many kinds of online betting, regardless of a 2011 Justice Department opinion that appeared to get rid of challenges.

While sports wagering is usually viewed in its own classification, "it clearly stays to be seen whether it gets the sort of momentum people believe it will," stated Keith Miller, law professor at Drake University and co-author of a book about sports wagering regulation.

David Carruthers is the former president of BetonSports, who was apprehended in the US in 2006 for running an offshore online sportsbook and served jail time.

Now a specialist, he says UK firms need to approach the market thoroughly, picking partners with caution and preventing mistakes that might result in regulator reaction.

"This is a chance for the American sports bettor ... I'm not exactly sure whether it is a chance for business," he says. "It really depends on the result of [state] legislation and how business operators pursue the chance."

'It will be partnerships'

As legalisation begins, sports betting firms are lobbying to fend off high tax rates, as well as demands by US sports leagues, which wish to gather a portion of profits as an "integrity fee".

International companies deal with the added difficulty of a powerful existing gaming market, with gambling establishment operators, state-run lottery games and Native American tribes that are seeking to safeguard their grass.

Analysts say UK companies will require to strike partnerships, providing their proficiency and innovation in order to make inroads.

They indicate SBTech's current statement that it is offering technology for Kentucky Derby operator Churchill Downs as an example of the kind of deals likely to materialise.

"It will be a win-win for everyone, however it will be partnerships and it will be driven by technology," Mr Hawkley stated.

'It will just depend'

Joe Asher, primary executive at William Hill US, is clear-eyed about the realities.

The business has been buying the US market because 2011, when it bought 3 US firms to establish a presence in Nevada.

William Hill now employs about 450 people in the US and has actually revealed collaborations with gambling establishments in Iowa and New Jersey.

It works as threat manager for the Delaware Lottery and has actually invested millions along with a local developer in a New Jersey horse racing track.

Mr Asher said William Hill has become a household name in Nevada however that's not necessarily the goal everywhere.

"We certainly plan to have a very considerable brand presence in New Jersey," he stated. "In other states, it will just depend on guideline and potentially who our regional partner is."

"The US is going to be the greatest sports wagering market worldwide," he added. "Obviously that's not going to happen on the first day."