Monday has not been a good day for the Broncos as far as injury news is concerned. Shortly after news broke that running back Javonte Williams has suffered a season-ending knee injury, linebacker Randy Gregory could miss anywhere from two to six weeks as he is set to undergo surgery on his injured knee, according to NFL Media

Specifically, Gregory will undergo arthroscopic surgery to trim the meniscus in his injured knee. Gregory's timetable for return will be determined based on the surgery. 

Gregory sustained the injury during Sunday's win over the Raiders. Through four games, the former Cowboy has tallied two sacks, two forced fumbles and nine tackles for the Broncos, who signed the 29-year-old veteran this past offseason. 

Gregory's presence has helped the Broncos boast the league's fifth-ranked scoring defense through four games. The unit is also fifth in the league in rushing yards allowed, eighth in third down efficiency and first in red zone efficiency. The play of Denver's defense has helped the Broncos split their first four games despite disappointing play from their offense thus far. 

Nik Bonitto, a second-round pick in April's draft, is in line to fill Gregory's spot in the starting lineup. Bonitto has appeared in two games this season while making appearances on defense as well as on special teams. He enjoyed a standout career at Oklahoma, where he racked up 16.5 sacks and 26.5 tackles for loss during his last two seasons in Norman.