The 31-year-old defender featured in 23 games in all competitions for the title holders last season, regularly suffering from fitness issues, and concerns were raised when he did not board the plane with the rest of the team to Bangkok on Wednesday.

However, the club have insisted that it is nothing for fans to worry about.

"It's nothing serious," a club spokesman told the club's official website.

"Nemanja has a touch of sciatica (pain stemming from nerves in the back) and may still join the tour at a later date.

"In the meantime, he'll continue his pre-season preparations in Manchester."

The club's pre-season tour will see them come up against Singha All Star XI on Saturday before they begin games against the A-League All Stars, Yokohama F.Marinos and Cerezo Osaka.