ENGLEWOOD, Colo. -- He's gotten bombarded on Twitter because, well, folks think he's another Brandon Marshall.

But @BMarshh54 is not the former Denver Broncos wide receiver now with the Chicago Bears who bears the same name. He is, however, the guy whom the Broncos will give the first chance to replace one of their most difficult players to replace on defense, injured linebacker Danny Trevathan.

Brandon Marshall will be filling in for the injured Danny Trevathan, the Broncos' top tackler in 2013. AP Photo

Trevathan suffered a medial tibial impaction fracture in his left leg during Tuesday's morning practice and is expected to miss six to eight weeks in his recovery. And while Broncos coach John Fox is not usually one to immediately declare the player who will replace an injured teammate, it was Marshall who got the first swing after Trevathan went down.

"I'm very confident," Marshall said. "Confidence is a big part of this game and I know I have the skill set; I have the mind to do it. So it's just a matter of the opportunity. So if I ever have the opportunity, I will get it done."

Marshall also worked in Trevathan's weakside linebacker spot later in the day as well when the team had an evening walk-through. He is expected to line up with the starters when the team returns to the field Thursday morning. Asked whether that's how it would go in the weeks to come -- the Broncos hope Trevathan will return to the lineup following their bye for a Week 5 game against the Arizona Cardinals -- Fox simply offered:

"Time will tell. In this league it's all about opportunity. We'll see what they do."

Marshall is first in line, with Lamin Barrow and Corey Nelson -- both Broncos draft picks this past May -- as fallback possibilities. But it's Marshall who has already lined up alongside Trevathan at linebacker in some of the Broncos' specialty packages during training camp, and it's Marshall whom the Broncos thought enough of to promote to the active roster from the practice squad just before the playoffs in December when Von Miller went to injured reserve.

This will be his opportunity, at least until Trevathan, who was the team's leading tackler last season with 129, returns to the lineup. The difficulty in replacing Trevathan, even over the short term, will be that the Broncos really don't have another player at the position who can do what Trevathan does as well as he does it.

Trevathan is stout enough to hold up in run defense along the line of scrimmage and athletic enough to work in coverage down the field. He has top-tier closing speed to the ball and he finishes plays when he gets there.

There will likely have to be a mix-and-match approach -- everyone will get a first look at that in Sunday's preseason game against the San Francisco 49ers -- until Trevathan's return. In large part that's because Marshall was already being used in one of the linebacker spots in the Broncos' nickel package before Trevathan was injured.

When the Broncos have lined up the second-team nickel in practice, it's been Barrow and Marshall at the two linebacker spots, so that will likely be how it looks with the starters now. Barrow has also worked as the backup middle linebacker in the base defense, and the Broncos liked his athleticism in his pre-draft work, as Barrow showed the ability in the high-powered SEC to shed blockers and get to the ball during his career at LSU.

"This is an opportunity for some young guys to get some work done," Fox said. "We'll hold down the fort until [Trevathan] gets back."