Watford have a mixed history of convincing the Football Association to give their young non-EU imports work permits in recent years, but could yet see 20-year-old Richarlison given the chance to play in the UK this season.

The young striker, who has been the star of Brazilian top flight Fluminense's season this year, is set to join the Hornets for a fee of around £11.2 million this week, having flown to London on Sunday before undergoing a medical examination.

But if he fails to earn a work permit, it will take the talented forward at least two years to earn EU citizenship before he has a chance of playing for the club.

The Football Association assesses every application submitted for players wishing to work in the UK before issuing recommendations to the Home Office, and has its own guidelines on who is likely to be eligible.

Those rules include earning a certain number of international caps, depending on the quality of the player's national side, or performances in big club tournaments like the Copa Libertadores, the South American version of the Champions League.

The transfer fee and wages are also taken into account, with more weight given to deals in the most expensive 25 per cent of transfers completed in the previous season.

On paper, this could make Richarlison's situation tricky. On the one hand, he has scored twice for Fluminense in this year's Copa Sudamericana, the second-tier continental competition in South America, similar to the Europa League.

However, he has yet to receive a full international call-up and his transfer value would, amid rising prices across the league, fall below anything likely to significantly influence the decision.

But sports lawyer Phil Hutchinson, of Mills and Reeve, says there is still a chance Richarlison, who has 10 Brazil Under-20 caps, could be granted a permit and be eligible for the start of the season.

"Players are meant to have a certain number of internationals in the last two years, but the FA have changed their approach slightly to take into account youth internationals," he said.

"Richarlison would have to go through the exemptions panel as he doesn't meet the objective criteria, where evidence gets shown to a three-man board with other critera you have to meet.

"That's where you look at things like the transfer value and wages. Last year the sum Watford are said to be paying would put them between 50 and 75 per cent of the way up the transfer fee list, and so you would get some credit for that.

"You can get extra points if you play in the Champions League or big games in your home country, and if he's a leading star for his team, that will make it easier."

The object of the work permit regulations are to make sure players entering the UK from outside the EU are of high quality - and there is scope, as seen previously with Isaac Success' successful application last year, for a convincing argument to be made on that front.

Hutchinson said: "The panel can look at his performances for the Under-20s but more generally there will be supporting statements given by players and managers he has worked with.

"If they can show he is going to be an asset to the league, they may be able to get him across. We've done permit work this summer with Colombians and Mexicans who didn't necessarily meet the requisite objective requirements, but it can come down to something as small as who is on the adjudicating panel."