Juan Mata
Juan Mata has endured an uncertain 14 months at Old Trafford.Getty Images

Former Manchester United defender Gary Neville has suggested Juan Mata's career at Old Trafford is uncertain as the Spaniard continues to be marginalised under Louis van Gaal.

Mata has made just two Premier League starts in 2015 and has struggled to adapt to the system employed by the former Netherlands coach.

The 26-year-old joined United from Chelsea for a then club-record fee of £37m in the 2014 January transfer window but Neville has said the midfielder's future is not secure given the plethora of options available.

"It's difficult at the moment to understand whether Falcao, Herrera, Mata, what is happening with them," he said. "Obviously Van Gaal has inherited Mata but he has a lot of those types of players in that sort of area.

"He's got Di Maria, Mata, Fellaini, Rooney; all number 10's of a different type or attacking midfield players. I am not sure [about Mata's future] he's a talented player, he's score goals but at the moment he seems out of favour."

Another United player who has failed to settle since a big money move to the club is Angel di Maria, with the British record transfer failing to live up to his £59.7m fee since moving from Real Madrid.

In stark contrast, Alexis Sanchez has flourished since moving from Real's La Liga rivals Barcelona, with the Chilean having netted 17 goals in his maiden campaign in English football.

But Neville does not believe Van Gaal made a mistake in signing Di Maria, despite his limited impact.

"Obviously Alexis Sanchez has had a far bigger impact and a better season than Di Maria," Neville added.

"But if you would have asked me at the start of the season; Sanchez or Di Maria - I would have said Di Maria. I like Sanchez as well, but I would have said Di Maria at the start of the season.

"I still think Di Maria and Shaw will prove to be fantastic signings for United, but they just need to perform to the level and they need to get the best out of them."