It was a frustrating Tuesday for Buffalo Bills running back LeSean McCoy who had to leave their practice because he injured his hamstring.

Sports Illustrated reported that the NFL player was seen grabbing his leg during their drills. He ended up being escorted by trainers from the field.

According to Bills coach Rex Ryan, the running back will have an MRI to check on his condition and that "next man up will have to step up" for the team especially with the series of injuries that haunted them.

"It's intact, not off the bone, so that's positive. Hoping it's not a pull, just a strain," Ryan said.

NBC Sports reported that the team is "getting really thin at running back," that's why not having McCoy on the team will hurt the Bills since he is vital for their offence buildup.

"He wasn't carted off, which may be a good sign. But it's reasonable for the Bills to worry when such a large part of their plan has a problem," NBC Sports said.

The 27-year-old is just on his first year with the Bills after he was traded from Philadelphia in exchange for linebacker Kiko Alonso.

Sports Illustrated said he was able to run 1,319 yards and make five touchdowns during his time with the Eagles in 2014.

His average for his six-year career is 4.6 yards and 54 touchdowns in total.

Meanwhile, ESPN explained that the team cannot afford any more injuries after running backs Fred Jackson, Boobie Dixon, Bryce Brown and Karlos Williams missed Tuesday's practice because of injuries.

To make things worse, wide receiver Percy Harvin is also believed to be out for a week due to hip soreness.

"He's so itching to get back, and that's why we sped it up. We were going to wait four days to give him the shot. We gave it to him early. Hopefully, he responds on it," Ryan said of Harvin.

The coach added that they are hoping the wide receiver will be able to return on Aug. 29 for their game versus the Pittsburgh Steelers.

If he will not be able to play by this time, the team expects Harvin to make it to the Sept. 3 match in Detroit.

"He doesn't want to go into [the regular-season opener] with no game work. He's trying to get back on the field," added Ryan.

The team is certainly hoping that sidelined players will be able to recover from their injuries and return to the team for their upcoming games.