GettyPeter McVitie'This season is survival of the fittest' - Erik ten Hag admits Man Utd 'need to catch up' with rivals and targets signings 'in all positions'Manchester UnitedE. ten HagTransfersPremier LeagueErik ten Hag has urged Manchester United to bring in more players in the summer transfer window to improve the depth of his squad.Article continues belowArticle continues belowArticle continues belowArticle continues belowUnited have made two major signings this summerTen Hag calls for further depth to be added to teamManager hopes to avoid last season's injury troubles