The 18-year-old is on the radar of manager Ole Gunnar Solskjaer on the advice of former United midfielder Darren Fletcher, but Werder are one of two German top-flight sides to have registered interest in the Irish-born defender.
The Red Devils are keen on more homegrown youngsters with huge potential and plenty of talents, and Collins impressed Fletcher during his stint with the Potters.
The teenager made just three appearances for the Championship outfit last term, but is set for a more prominent role next term, with Stoke refusing to release him to Ireland for the Under-19 European Championships this month as he is currently training with the senior team in pre-season.
Collins will be linking up with United’s under-23 if he is snapped up, but he could force soon his way into the senior team if he does enough to impress Solskjaer and the youth team coaches.
The 6ft 5in centre-back has a very bright future ahead of him, and Stoke are expected to do everything within their power to convince him to stay.