Steve Luciano/Associated Press
FLORHAM PARK, N.J. — Sam Darnold has mononucleosis and will not play on Monday night against the Cleveland Browns (0-1), Jets head coach Adam Gase announced Thursday. There is no timetable for his return.
Darnold was originally diagnosed with strep throat Tuesday night, but further tests revealed he had mono. Trevor Siemian, who signed with the Jets in March, will start in his place Monday night. Siemian has not played in an N.F.L. regular season game since Dec. 14, 2017.
Monday’s matchup is the start of a tough stretch in the schedule for the Jets, who will face the Patriots in Foxborough, Mass.