Burnley - Anthony Martial faces an anxious wait to discover if he still has a Manchester United future under beleaguered boss Jose Mourinho when his side face a crucial clash at Burnley on Sunday.

Martial has seen his relationship with the United manager deteriorate since his agent declared the French forward wanted to leave Old Trafford to try and resurrect his international career.

The matter reached its low point during United's pre-season tour of the United States when Martial left to return to Europe for the birth of his child and then reportedly refused to re-join the team in America.

That stand-off resulted in Martial being fined by the club - the only time that has happened in Mourinho's reign, according to the manager himself - and his involvement during United's difficult start to their Premier League campaign has, so far, been limited.

An unused substitute for the opening day win over Leicester, Martial started in the disappointing loss at Brighton, only to be replaced after an hour, and was not even named on the bench for Monday's home defeat by Tottenham.

But while it was widely accepted that Mourinho would have been prepared to allow Martial to leave Old Trafford this summer for the right price, his employers did not share his opinion.

United's owners, having paid Monaco £36 million ($46 million) for a player who is still only 22, seemed keen to keep the striker at the club in the hopes that he could develop and rediscover the form he showed in an electrifying start to his United career in 2015.

To that end, United reportedly opened discussions with Martial this week designed to tie him to a new, long-term deal.

Martial has less than 12 months remaining on his base deal but, as is common practice with United contracts, the club can, and will, exercise an option that extends until the summer of 2020 and avoids him leaving for free at the end of the current season.

However, United are understood to be talking to Martial's representatives about a new, five-year contract extension, a development with which Mourinho is in full agreement, according to reports.

Mourinho would not discuss the contract situation before the game although he appeared to confirm that contract talks are progressing and, possibly, close to a resolution.

"We have to wait for this to be official because at the moment it is not official," he said.

Given Mourinho's managerial track record of leaving several of his former clubs within three seasons, it appears common sense that Martial will outlast his manager at Old Trafford should he sign such a deal.

But, having missed out on a place in France's World Cup winning squad this summer, Martial will be more concerned about his short-term prospects under a manager who appears to be coming under increasing scrutiny and pressure with every passing week.

United have won their last two visits to Turf Moor without conceding a goal and Martial has scored in each of them.

After United's failure to turn a dominant opening half-hour against Tottenham into goals, Mourinho could well decide to start Martial against Sean Dyche's team.

While Romelu Lukaku appears an automatic choice as centre-forward, there may also be a role for Alexis Sanchez who is now close to full match fitness.

Defender Phil Jones will be absent, having injured his hamstring against Tottenham.

Mourinho scouted Burnley as they exited the Europa League against Olympiakos on Thursday and said: "I went there and knew they would rest a lot of players who will play Sunday but they were very unlucky to go out."