London - With the fate of Brexit shrouded in uncertainty, Britain's sporting world is increasingly concerned about the impact for players, fans and investors.
New restrictions on immigration from the EU after Brexit is a particular issue for football, although some see this as a positive for British players.
Access to top European talent such as Chelsea's Belgian playmaker Eden Hazard is particularly important for the Premier League, the world's most lucrative domestic football league.
The Premier League said earlier it has had "positive discussions with government about the importance of access to European players for our clubs, and the many cultural and economic benefits a globally popular Premier League brings to the UK".
Just like in Britain as a whole, however, football team owners are divided on the pros and cons.
Steve Lansdown, the billionaire owner of second-tier side Bristol City, was one of the most high-profile business figures to support exiting the EU and believes football can benefit.
"Fewer people from abroad will come in," he told AFP.
"Clubs will be more selective and the prospective players from abroad will have to pass a test.
"It will give more opportunity to English players to come through."
Phil Garlick, chairperson of Premier League side Burnley, instead has warned Brexit could be "hugely damaging" to English football and supports a second referendum.
"Ending freedom of movement will make it much more difficult for teams to attract the right talent, if the government brings in more restrictive conditions for work visas for players from Europe," he has said.
Though less reliant on foreign players, rugby is also following the political wrangling closely because of the potential implications for European tournaments.
The first major test will come on March 29, 2019, the day Britain is due to exit the European Union.
It is also the day when the quarter-finals of European club rugby's competitions get underway, which could mean travel chaos for teams and supporters alike.
For the moment, the competition's organisers, Switzerland-based European Professional Club Rugby (EPCR), told AFP "they are closely monitoring the terms of the United Kingdom's exit from the European Union."
Simon Keogh, the CEO of Rugby Players Ireland, said Brexit could prove costly to the Irish Rugby Football Union (IRFU) or for Ulster players like Ireland captain Rory Best.
"They are paid in sterling but that and their bonuses, which are negotiated in euros, will be affected if sterling spikes," Keogh told AFP.
"This more than the travel issue is potentially more volatile.
"It isn't that the boys are too motivated by the money but they still have to pay their mortgages."
A negative impact on incomes would be particularly unwelcome for Irish players at the moment.
Irish rugby is experiencing an annus mirabilis with Irish province Leinster the current European champions while the national side swept the Six Nations Grand Slam and beat world champions New Zealand in November.
Britain boasts a Formula One world champion in Lewis Hamilton and is home to several teams including Renault, Williams and McLaren which also employ many foreign staff.
Renault's Executive Director Marcin Budkowski said there could be a rocky road ahead, again because of the changes to immigration rules.
"Potentially yes it could be a problem," he told AFP.
"We employ different nationalities... How easy will it be to hire foreigners in the future? One doesn't know. Probably more difficult than now but there again the English are pragmatic," he said.
Race horses and breeding stock are also reliant on easy movement across borders, as well as investor backing, and the prospect of a no-deal Brexit is proving harmful.
"I think Brexit causes uncertainty to people in the financial world," said Edmond Mahony, chairman of Europe's oldest and leading bloodstock sales company Tattersalls.
"That is bad for racing because lots of owners work in it (financial world) and are unsettled and potentially they could have decided not to be involved in the market this year."
English training great John Gosden is downbeat about what the future holds.
"We are dealing with a massive train wreck right now," he told AFP.
"We need to be able to move horses around, they can't sit and wait at a port for two to three days waiting for someone to stamp their passport.
"I hope common sense prevails in the end, I really hope it will. If it damages everybody what is the sense of it?"