It's high stakes for UK firms as sports betting starts to spread in America.

From Tuesday, brand-new guidelines on wagering entered result in Delaware, a tiny east coast state about 2 hours from Washington.

Neighbouring New Jersey might begin accepting sports bets as early as Friday.

The changes are the first in what might end up being a wave of legalisation after the Supreme Court last month cleared the way for states to allow sports wagering.

The market sees a "when in a generation" opportunity to establish a new market in sports-mad America, said Dublin-based financial expert David Jennings, who heads leisure research study at Davy.

For UK firms, which are facing debt consolidation, increased online competition and tougher rules from UK regulators, the timing is particularly suitable.

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But the industry says counting on the US stays a dangerous bet, as UK companies face complicated state-by-state policy and competition from established local interests.

"It's something that we're truly concentrating on, however similarly we do not desire to overhype it," stated James Midmer, spokesperson at Paddy Power Betfair, which recently bought the US dream sports website FanDuel.

'Take time'

The US accounted for about 23% of the world's $244bn (₤ 182bn) in video gaming income in 2015, according to a report by Technavio, external released in January.

Firms are hoping to use more of that activity after last month's decision, which overruled a 1992 federal law that disallowed states outside of Nevada and a couple of others from authorising sports betting.

The judgment found the law was an over-reach of federal power. But the court it did not actually legalise sports betting wagering, leaving that concern to regional lawmakers.

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

Potential profits varieties from $4.2 bn to almost $20bn every year depending on elements like the number of states relocate to legalise, Oxford Economics approximated in a 2017 study for the American Gaming Association.

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

Now, he said: "I think 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 require time'."

'Remains to be seen"

Chris Grove, managing director at Eilers & Krejcik Gaming, predicts that 32 states will legalise sports wagering in some type by 2023, creating a market with about $6bn in yearly earnings.

But bookies deal with a far different landscape in America than they do in the UK, where betting shops are a frequent sight.

US laws restricted betting largely to Native American lands and Nevada's Las Vegas strip until reasonably just recently.

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

States have also been slow to legalise many kinds of online gambling, in spite of a 2011 Justice Department opinion that appeared to get rid of challenges.

While sports betting is generally viewed in its own classification, "it plainly remains to be seen whether it gets the sort of momentum individuals think it will," said Keith Miller, law teacher at Drake University and co-author of a book about sports wagering guideline.

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

Now an expert, he states UK firms must approach the marketplace thoroughly, picking partners with care and avoiding missteps that might cause regulator reaction.

"This is an opportunity for the American sports gambler ... I'm uncertain whether it is an opportunity for business," he says. "It truly depends on the outcome of [state] legislation and how business operators pursue the opportunity."

'It will be collaborations'

As legalisation starts, sports wagering companies are lobbying to ward off high tax rates, as well as demands by US sports leagues, which desire to gather a percentage of income as an "integrity charge".

International companies face the added obstacle of an effective existing gaming market, with gambling establishment operators, state-run lottos and Native American tribes that are seeking to safeguard their turf.

Analysts state UK companies will require to strike collaborations, using their proficiency and technology in order to make inroads.

They point to SBTech's recent announcement that it is supplying 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 collaborations and it will be driven by technology," Mr Hawkley said.

'It will simply depend'

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

The company has been buying the US market since 2011, when it bought three US companies to develop a presence in Nevada.

William Hill now utilizes about 450 individuals in the US and has actually announced collaborations with gambling establishments in Iowa and New Jersey.

It works as danger supervisor for the Delaware Lottery and has actually invested millions together with a local designer in a New Jersey horse racing track.

Mr Asher stated William Hill has become a family name in Nevada but that's not necessarily the goal everywhere.

"We certainly intend to have an extremely considerable brand name presence in New Jersey," he said. "In other states, it will just depend upon policy and potentially who our local partner is."

"The US is going to be the biggest sports wagering market in the world," he included. "Obviously that's not going to occur on day one."