Buffalo Bills running back LeSean McCoy could miss the rest of October after an MRI revealed a "new tear" in his hamstring, according to Fox Sports Mike Garafolo.

This new injury means that McCoy is likely to miss three to four weeks. McCoy said he wouldn't return until his hamstring is "100 percent" healed, via CBSSports.com.

The Bills traded for McCoy this offseason, but injuries have plagued his start in Buffalo. In three games played this season, McCoy has rushed for 43 yards with no touchdowns. Luckily for the Bills, rookie running back Karlos Williams has played big.

Williams had a huge week against the Dolphins last Sunday, rushing for 110 yards and a touchdown. The rookie running back has scored a touchdown in every game, and it looks as though he is headed for a starring role on this team.

The Bills are 2-1 but will likely need to improve immensely to catch up with the New England Patriots. While the Patriots seem to have control of the division, new head coach Rex Ryan has their defense at the top of the league. The Bills have the best rush defense in the league after three games, and Ryan is likely a big part of that.

The Bills offense is producing as well, and they are third in the league in terms of points scored per game. Quarterback Tyrod Taylor has played well in his first three starts for the team and has already thrown seven touchdowns and rushed for one as well. Taylor and the offense will likely be anxiously waiting for McCoy's return because they likely know the dynamic player he can be.

The Bills are likely going to be cautious with McCoy, as he signed a five-year contract worth $40 million this offseason. McCoy could miss the rest of October, and the Bills could be fine with that as long as their rookie running back Williams continues to produce.