Mason Greenwood -- star forward for Manchester United -- is no longer facing charges for attempted rape and assault ... after he was arrested for the alleged crimes last year.

The Greater Manchester police announced prosecutors dropped the charges on Thursday ... saying the 21-year-old soccer player will "no longer faces criminal proceedings in relation to this."

As for why they opted to no longer pursue the serious charges, The Athletic spoke to prosecutors handling the case who said it was a "combination of the withdrawal of key witnesses and new material that came to light", saying "there was no longer a realistic prospect of conviction."