PITTSBURGH -- Quarterback Kenny Pickett is expected to be sidelined "a couple weeks" with a right ankle injury he sustained Sunday in the loss to the Arizona Cardinals, a league source told ESPN's Adam Schefter.
With Pickett sidelined, backup quarterback Mitch Trubisky is expected to start Thursday against the New England Patriots.
"We'll roll with Mitch if [Pickett] can't play," coach Mike Tomlin said immediately after the loss.
Pickett sustained the injury midway through the second quarter of the Pittsburgh Steelers' 24-10 loss to the Arizona Cardinals and did not return.
Trubisky took over in his absence and finished the game 11-of-17 for 117 yards and a touchdown. He also lost a fumble.
Earlier this season, Pickett was knocked out in the Week 8 loss to the Jacksonville Jaguars with a ribs injury, but he returned four days later and played against the Tennessee Titans in the team's first Thursday night game.
Since taking over the starting job early in his rookie season, Pickett hasn't missed a start since Week 15 last season when he was out with a concussion. The Trubisky-led Steelers beat the Carolina Panthers 24-16 in Pickett's absence.
Pickett was not the only Steeler to sustain a serious injury Sunday. Safety Minkah Fitzpatrick, playing in his first game in a month, broke his left hand in the second quarter. Fitzpatrick's hand was casted during the first of two lengthy severe weather delays, and he didn't miss any snaps. He also said he expects to play Thursday.
"I couldn't grab with it," Fitzpatrick said. "But I was able to still play and didn't miss any plays. ... I think I did it making a tackle and then a few plays later, I tried to punch with it, and that's when I really noticed it.
"... I'll be fine. We'll probably just wrap it up, clip it up like we did today and keep it moving."
While Fitzpatrick was able to play through his second-quarter injury, Pickett was not.
Pickett sustained the injury when he kept the ball on third down near the Steelers' goal line and scrambled forward, diving for the end zone. Cardinals defensive lineman Jonathan Ledbetter dove to tackle Pickett from behind.
Pickett tried to get up after Ledbetter's hit but dropped back to the ground, and athletic trainers ran out to care for him. He eventually walked off the field mostly under his own power with a limp.
After being evaluated in the blue sideline medical tent, Pickett went back to the locker room for the rest of the second quarter, and he was ruled out before play resumed following a severe weather delay during halftime.
Pickett later returned to the sideline with a walking boot on his right ankle. He entered the game with right ankle discomfort sustained in the win against the Cincinnati Bengals.
Trubisky came on for a fourth-and-goal play from the 1 immediately after Pickett's injury. The Steelers failed to punch it in when running back Najee Harris was stopped short of the goal line. The Cardinals then went on a 99-yard scoring drive to take a 10-3 lead into halftime.
"It was a significant point in the game when we got stopped in the red zone and then they drove the ball there before the half, but that doesn't tell the story to the game, man." Tomlin said. "We just weren't good enough throughout the game. We didn't play a good game today."
Pickett has exited two other games early with injuries this season. Pickett sustained a bone bruise late in the third quarter of the Steelers' Week 4 loss to the Houston Texans and a rib injury just before halftime of the Week 8 loss to the Jaguars. Trubisky finished each of those games for the Steelers. In those two appearances, Trubisky went 18-of-32 for 156 yards with one touchdown and two interceptions.
Against the Cardinals, Trubisky led the offense to a late fourth-quarter score, capping a 75-yard drive with a two-yard touchdown to Diontae Johnson. Two plays earlier, Trubisky connected with Johnson for a 26-yard gain.
"We went down, we finished down in the red zone," Trubisky said. "The guys aren't giving up towards the end. So when it gets sloppy like that, everyone stuck together. We put a drive together, put some points on. So I think you look at that drive, and you try to take away some positives.
"But for me it's simple. We got to clean up the non-talent issues, getting lined up the penalties and just playing 11 guys that as one."
Not only did Pickett get knocked out of the game before halftime, but the Steelers also lost two more starters in the first half: inside linebacker Elandon Roberts with a groin injury and guard Isaac Seumalo with a shoulder injury.
With Roberts out, Tomlin said, the defensive communication suffered. The Steelers allowed the Cardinals to season-high 10 third-down conversions, the most they've allowed in a game since 2012.
"It's hard when you get depleted inside," linebacker T.J. Watt added. "But it's not an excuse. We need to have guys step up in situations. That's including myself. And we weren't able to do that today."
With Roberts dealing with a groin injury on a short week, the Steelers may have to turn to former Green Bay inside linebacker Blake Martinez, who the team recently signed off the Carolina Panthers' practice squad. Martinez has been inactive in each of the two games since he joined the Steelers' 53-man roster, but the inside linebacker cupboard is growing more and more bare with earlier season-ending injuries to Cole Holcomb and Kwon Alexander.
The Steelers also made the post-trade deadline addition of former Falcons linebacker Mykal Walker, who played 98.6% of defensive snaps against the Cardinals, and signed Myles Jack to the practice squad, ending his brief retirement.