Denver Broncos starting tight end Joel Dreessen will undergo his second knee operation in four months, USA Today reported Sunday.
The Denver Post had reported Saturday that Dreessen had a setback in his recovery from his May arthroscopic procedure on his left knee, and will be sidelined for the rest of training camp.
Now he reportedly will undergo a second arthroscopic procedure to clean up some issues in the same knee.
Dreessen had practiced with the team through Friday without any reports of problems with his knee. He then sat out Saturday's practice because of pain in his knee, and now he is out for an extended period.
It is unclear whether Dreessen will miss the start of the regular season.
Dreessen started 15 regular-season games last season and had 41 receptions for 356 yards and five touchdowns.