By Editor Wayne Veysey 

Eric Dier’s fitness has hit the ‘red zone’, the point of fatigue where sportsmen are at a major risk of injury, Football Insider sources understand.

The midfield anchorman was omitted from the Tottenham squad that lost 3-0 to Borussia Dortmund in midweek due to concerns about his fitness.

Manager Mauricio Pochettino was criticised by some pundits and supporters for not only leaving Dier in England but also relegating key duo Harry Kane and Mousa Dembele to the substitute’s bench on Thursday night in the first leg of the Europa League double-header.

A well-placed source has told Football Insider that Dier was given a rest because of the amount of football he has played this season.

Dier has made 41 appearances for Tottenham this season, a record matched in the squad only by Harry Kane, although the midfielder has played more minutes – 3474 – than his countryman, who has totted up 3218 minutes.

The 22-year-old has been wearing a GPS vest in training this week to provide feedback to fitness and coaching staff, who can then assess whether to tailor his training schedule accordingly. The vest collects a multitude of statistics on speed, distance, heart rate, dynamic stress load, accelerations and decelerations.

Maurcio Pochettino has steered Tottenham to the verge of a title challenge

Red zone: Dier has played more minutes than any Spurs player this season

The England international was taken out of the firing line for the trip to Germany because of fears his workload has increased the risk of him getting injured in the final stages of the season.

Nevertheless, Dier is set to return for Sunday’s Premier League clash against Aston Villa as Spurs attempt to keep the pressure on leaders Leicester, who host Newcastle on Monday night.

In other Tottenham team news, Dele Alli is set to return to the team on Sunday after being suspended in midweek.