Las Vegas Raiders coach Jon Gruden used racist language to describe the head of the National Football League Players Association, the Wall Street Journal reported Friday.

Gruden used anti-Black imagery to describe NFLPA executive director DeMaurice Smith in an email sent to a team executive on July 21, 2011, according to the Journal. 

“Dumboriss Smith has lips the size of michellin tires,” Gruden wrote in the email to Bruce Allen, the former president of the franchise now known as the Washington Football Team, the Journal reported.

The NFL is reviewing Gruden’s status with the Raiders for potential discipline, the Journal reported, citing a source familiar with the matter.

In response to the report about Gruden’s remark, Smith said that it isn’t the first racist comment he’s been subject to and “probably will not be the last.”

“This is a thick skin job for someone with dark skin, just like it always has been for many people who look like me and work in corporate America,” Smith said in a statement. “You know people are sometimes saying things behind your back that are racist just like you see people talk and write about you using thinly coded and racist language.” 

When Gruden sent the email, the NFL and its players were attempting to resolve a lockout, the Journal reported. It was a work stoppage imposed by the league’s owners that lasted from March 12, 2011, to July 25, 2011.

While the NFL’s owners voted to ratify a new collective bargaining agreement on July 21, players opted out of the vote.

Gruden cited the lockout for upsetting him at the time of his racist remarks, according to the Journal. He said he did not trust the stance of the NFL players, who were led by Smith, in the negotiations.

Gruden added that he has referred to people he believes are lying as “rubber lips” in the past, and that he took it “too far,” according to the Journal.

“I was upset,” Gruden told the Journal. “I used a horrible way of explaining it.” 

“I don’t think he’s dumb. I don’t think he’s a liar,” Gruden said. “I don’t have a racial bone in my body, and I’ve proven that for 58 years.” 

The revelation about Gruden’s remark comes as Smith’s position as executive director of the NFLPA hangs in the balance.

On Tuesday night, the NFLPA’s executive committee voted to determine whether Smith should be allowed to remain in the job he has held for the past 12 years, ESPN reported Wednesday. The 14-member committee was evenly split in a vote of 7-7.

The NFLPA’s 32 team player representatives are set to vote on Smith’s status on Friday at 6 p.m. ET, according to ESPN.

CNBC’s Jabari Young contributed to this report.