Diggs suffered the injury during a one-on-one period in practice and was briefly spotted inside the team facility on crutches before undergoing an MRI, which revealed the tear.
It is a massive loss for a Cowboys defense that is ranked No. 1 in the NFL in yards allowed and points per game through two weeks. Since entering the NFL in 2020, Diggs has 18 interceptions -- tied for the most in the NFL with J.C. Jackson of the Los Angeles Chargers.
Meanwhile, Cowboys Pro Bowl center Tyler Biadasz hurt a hamstring during Thursday's practice and is undergoing an MRI to determine the extent of the injury, a source told ESPN's Adam Schefter. Another source told Schefter, "Tyler will be OK."
Cowboys star edge rusher Micah Parsons reacted to the Diggs news with a post to X:
I am my brothers keeper! I got you 7! No more need to be said! 🦁🦅 pic.twitter.com/8ujEMegYuP— Micah Parsons (@MicahhParsons11) September 21, 2023
According to NFL Next Gen Stats data, Diggs has allowed just three catches for 31 yards on eight targets as the nearest defender in coverage this season. Quarterbacks have a 9.9 passer rating on throws with Diggs as the nearest defender. Diggs has forced a fumble, intercepted a pass and recorded three pass breakups while being credited with six tackles in two games.
Diggs signed a five-year, $97 million contract extension with the Cowboys during training camp -- a deal that included a $21.25 million signing bonus and $42.3 million guaranteed. After missing four games with a foot injury in 2020, Diggs had missed just one game in each of the past two years.
With Diggs out, the Cowboys can move DaRon Bland to outside cornerback opposite Stephon Gilmore, who was acquired in an offseason trade with the Indianapolis Colts. Jourdan Lewis can return to his role in the slot. Last week, Lewis played in his first game since suffering a serious foot injury in October, seeing 10 snaps of action.
Bland, who led the Cowboys with five interceptions last season, returned an interception for a touchdown in the season-opening win against the New York Giants.
The Cowboys also have Noah Igbinoghene, a 2020 first-round pick of the Miami Dolphins they acquired at the start of the month in a trade, and rookie Eric Scott at cornerback. Nahshon Wright is on injured reserve with an ankle injury and can return to game action in Week 5.