The New York Giants could lose quarterback Jaxson Dart for the rest of the season after postgame testing suggested his left knee injury is more serious than early reports indicated, leaving surgery as a possible outcome.

ESPN coverage on Tuesday said further imaging and evaluation have raised the prospect that Dart may require a procedure that would sideline him long term. Adam Schefter reported the results of additional tests have forced the Giants to consider a season-ending operation.

Dart was injured on the opening possession of Monday night’s 28-6 defeat by the Los Angeles Rams. Initial information from the club described a sprain to the medial collateral ligament and said he had not suffered any fractures, with an MRI scheduled for Tuesday to clarify the extent of the damage.

Head coach John Harbaugh told reporters he believed a "devastating outcome" had been avoided and said he did not expect Dart to miss extended time, though he declined to provide a precise recovery timetable.

The 23-year-old, who started the season with a strong showing in New York’s Week 1 win over Dallas, left the field after he absorbed a heavy hit from Byron Young and Josaiah Stewart on the Giants’ seventh play on Monday. He watched the second half from the sideline in a tracksuit while Jameis Winston replaced him under centre.

Winston struggled to spark the offence after taking over, throwing an end-zone interception as the Giants’ only points came from field goals in the loss. The result leaves New York without offensive momentum and facing immediate roster and depth decisions if Dart is unavailable for an extended stretch.

The wider NFL also saw significant quarterback injuries in Week 2, with Caleb Williams declared week-to-week after a hamstring issue and Jayden Daniels sidelined by a dislocated left elbow with no set return date. The Giants now await the full MRI findings and any surgical determinations that will define their short-term plans.