Winston doubtful for London game vs. Vikings, Thomas ruled out
Meanwhile, receiver Michael Thomas has been ruled out with a foot issue. Winston and Thomas missed their third straight practice session Friday.
Veteran Andy Dalton will get the start if Winston is unable to play.
Winston sustained the back injury in the season opener but has played through the ailment up until now.
The signal-caller has struggled to start the season, throwing for 858 yards and four touchdowns against five interceptions.
Thomas, the former Offensive Player of the Year, is second on the team in receiving yards (171) and first in touchdown receptions.
Both Winston and Thomas were looking to put their injury issues behind them in 2022. The former suffered a torn ACL midway through last season, while the latter missed all of 2021 and most of 2020 with ankle injuries.
New Orleans also ruled guard Andrus Peat (concussion) and safety Marcus Maye (rib) out of Sunday's contest. The team listed running back Alvin Kamara (rib) and receiver Jarvis Landry as questionable, but both were able to practice in multiple sessions.
The Saints enter Week 4 with a 1-2 record after losing back-to-back games against the Tampa Bay Buccaneers and Carolina Panthers.