Jalen Thompson had made his way from supplemental draft pick a summer ago to starting safety for the Cardinals, but he was only two plays into Year Two before hitting a detour.

Thompson, who hurt his ankle tackling 49ers running back Raheem Mostert, missed the rest of the win Sunday and then was placed on injured reserve Thursday.

The Cardinals replaced him on the roster with veteran safety Curtis Riley, whom they plucked off the Steelers' practice squad. Riley initially made the Steelers' 53-man roster after training camp and had played 16 games in each of the past two seasons – in 2019 with the Raiders and in 2018 with the Giants. In New York that season, Riley started all 16 games and made four interceptions.

"You are concerned (Jalen is) a young player," defensive coordinator Vance Joseph said. "When they miss time you're concerned about the football IQ going the wrong way, but he's in meetings every day and hopefully we can keep him around and keep studying and keep watching tape. Coach Marc Rob (Marcus Robertson) spends a lot of time with him outside scheduled meetings."

With the new COVID-19 rules for the 2020 season, an IR stint does not have to be a season-wrecker. This year, a player has to only spend a minimum of three weeks on IR – in a normal season, it's at least eight weeks.

Chris Banjo would be the replacement of Thompson in the starting lineup. The veteran had a solid game in Thompson's place in San Francisco, and even had an interception, although it was wiped out because of a penalty. The Cards also could activate second-year safety Deionte Thompson.

"(Jalen's) best trait is open-field tackling," Joseph said. "We have to get Banjo and D.T. to replace J.T. When that ball pops down the middle, it cannot be a 65-yard touchdown. Worst case it's a 30-yard gain and we play again. But we cannot let the ball run through the middle of the defense for 65 yards. That's high school football. That can't happen in this league."