Vikings place rookie DE Janarius Robinson on injured reserve, sign RB Ito Smith

The Vikings' depth at defensive end took a hit during Saturday's preseason loss to the Colts when rookie Janarius Robinson suffered a season-ending injury. Robinson, the fourth-round pick out of Florida State, was placed on injured reserve Monday, the same day the team finalized an agreement to bring back defensive end Everson Griffen.

Robinson watched practice Monday with a wrap on his leg, indicating a lower-body injury. Per NFL protocols, he is out for the season, as only players who are placed on I.R. after the initial 53-man regular season roster is set are eligible to return.

Alexander Mattison also apparently picked up an injury after playing just two snaps against the Colts. He and fellow running back Kene Nwangwu, who hyperextended his knee in the Aug. 14 exhibition opener vs. the Broncos, were held out of Monday's practice.

So the Vikings signed former Falcons running back Ito Smith, who was already taking 11-on-11 reps with the third-string offense on Monday in a No. 20 jersey. Smith was most recently in Cardinals training camp this month for nine days before he was released.

The Vikings also waived defensive tackle Jordon Scott with an injury designation; he will revert to the team's IR if he goes unclaimed on waivers. Quarterback Danny Etling and linebacker Christian Elliss were also waived as the team needs to get to a leaguewide 80-player roster limit by Tuesday afternoon.

Barr, Richardson not spotted

Eight Vikings players, including linebacker Anthony Barr and defensive tackle Sheldon Richardson, were sidelined at Monday's practice.

The team is treating Barr's health with "kid gloves," coach Mike Zimmer said Saturday, but the nature of his injury has not been disclosed.

Receiver Adam Thielen (quad), tight end Tyler Conklin (hamstring), Mattison (undisclosed), Nwangwu (knee), tackle Christian Darrisaw (groin) and guard Dru Samia (undisclosed) also did not practice Monday. Thielen has a thigh bruise suffered early in Saturday's game, according to Zimmer.

Safety Xavier Woods put on pads and warmed up with the team, but he left to rehab an undisclosed injury on his own. Rookie safety Camryn Bynum got first-team reps next to Harrison Smith. Nose tackle James Lynch, who injured his ankle in the preseason opener, also warmed up in pads, but quickly shed them to rehab his injury off to the side.

Jefferson dons red jersey

Halfway through Monday's practice, receiver Justin Jefferson ditched his typical white practice jersey in favor of a red, no-contact No. 18 that didn't even have his name on the back. Whose idea was it for Jefferson to wear the cautionary jersey as he practices through the soreness of his injured right shoulder?

"Zim's," Jefferson said as he walked off the practice field.

Cornerback Patrick Peterson still got his hands on Jefferson as they competed during 11-on-11 reps in Monday's practice, but no one brought Jefferson to the ground. His right shoulder appeared fine as he threw deep balls to other receivers after practice.