HENDERSON, Nev. — Las Vegas Raiders safety Lonnie Johnson Jr. suffered a broken fibula during Saturday’s practice at Allegiant Stadium, a source told ESPN’s Jeremy Fowler.

Johnson will get an MRI to determine if there is additional damage.

The six-year veteran was carted off the field after he collided with defensive end Maxx Crosby while attempting to tackle running back Raheem Mostert.

Johnson, a projected backup, has been competing for a rotational role in the Raiders’ secondary. During training camp, he has received first-team reps whenever the defense has three safeties on the field. Johnson and Isaiah Pola-Mao would line up in the traditional safety spots, while Jeremy Chinn played nickel.

The 29-year-old Johnson signed a one-year deal with the Raiders this offseason. He and Chinn were among the additions at safety following the departures of Tre’von Moehrig and Marcus Epps.

Las Vegas also signed veteran safety Jamal Adams, who has converted into a weakside linebacker.

Johnson, a second-round pick by the Houston Texans in 2019, has played for five teams during his pro career. In 83 games, he has collected 199 tackles, 15 passes defended and four interceptions.