GLENDALE, Ariz. -- Cardinals cornerback Starling Thomas V tore his left ACL near the end of Friday's practice, a source told ESPN's Adam Schefter on Sunday.
The Cardinals placed Thomas on season-ending injured reserve Sunday and signed cornerback Steven Gilmore in a corresponding move.
Thomas went down during an 11-on-11 session and had to be carted off the field. Tests on Sunday revealed the ACL tear.
With Thomas' injury, the Cardinals lose experience in a young cornerbacks room. He started 15 of 17 games last season, allowing 32 catches for 434 yards and three touchdowns, according to NFL Next Gen Stats.
However, the Cardinals are equipped to handle Thomas' absence because of depth at the position added this offseason. Arizona has Garrett Williams, who spent time as the nickel last season and started 11 games, and Max Melton, who came along in the second half of last year and started three games.
Behind them are two rookies, second-round pick Will Johnson, who got reps with the first team during the first week of training camp, and fifth-round pick Denzel Burke, as well as returners Kei'Trel Clark and Elijah Jones.
On Friday, general manager Monti Ossenfort said Johnson has been impressive early in camp.
"He's had a good couple of days here," Ossenfort said. "He stacked a few days together, and so that's great to see."