Manchester United need to spend big again in 2015 before the club can once more be seen as title contenders, according to former Red Devils defender Phil Neville.

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United's seventh-placed finish in the Premier League last season led new coach Louis van Gaal, appointed in place of David Moyes, to splash out over 150 million pounds on Angel Di Maria, Luke Shaw, Ander Herrera, Marcos Rojo, Daley Blind and loan signing Radamel Falcao.

Absent from that list, however, was an out-and-out central defender, a position which has seen United struggle this season as Chris Smalling, Phil Jones and Jonny Evans battle for form and fitness and youngster Tyler Blackett seeks to establish himself.

And Neville, who spent a decade as a professional at Old Trafford having come through the club's youth system and worked as a coach for Moyes last season, believes that is the biggest issue still to be addressed.