Ausberry has not practiced this week and did not attend Tuesday's workout as a spectator, like the rest of Oakland's injured players. Coach Dennis Allen was tightlipped when discussing the issue and didn't disclose the exact nature of the injury or what knee Ausberry hurt.
''He's got a knee (injury),'' Allen said. ''It looks like we're probably going to have to do a procedure on that knee, so he may be out for a little while.''
The Raiders lose their best blocking tight end with Ausberry sidelined.
That's critical because Oakland is hoping to improve a running game that has been mediocre for the past several seasons.
Mychal Rivera, a sixth-round draft pick in 2013 who was third on the team with 38 receptions, 407 yards and four touchdowns, is expected to replace Ausberry in the starting lineup.
Oakland plays its first preseason game against the Minnesota Vikings on Friday.
''The sky's the limit with this offense,'' said Rivera, who had three starts as a rookie. ''Expectations are high for me, this offense, and I'm excited to see what we can do.''
Ausberry hasn't had much good fortune the past few years.
A seventh-round draft pick who was a wide receiver at USC, Ausberry missed all of 2013 after suffering a serious shoulder injury during the Raiders' second preseason game in New Orleans. He was penciled in to be the starter before getting hurt, similar to the situation now.
Ausberry eventually had shoulder surgery and was placed on season-ending injured reserve.
Despite that, he was listed as Oakland's starter when the team released the first depth chart of camp. Ausberry outplayed Rivera for the top spot, though Rivera has been the better receiver of the two so far in camp.
Ausberry's injury leaves a void.
Oakland has six tight ends on its training camp roster. Ausberry is the senior member of the group that includes Rivera, Nick Kasa, Brian Leonhardt and rookies Jake Murphy and Scott Simonson.
Allen didn't sound as if Ausberry's injury is serious and was non-committal when asked if the fourth-year tight end is expected back before the end of the preseason.
''We should be able to get him back at some point and time,'' Allen said. ''I don't know how long that is going to be. We'll have to evaluate that as we go along.''
Notes: Wide receiver Greg Little, who missed time earlier in camp with a hamstring injury, practiced for a second consecutive day without a setback and hauled in a long touchdown pass from quarterback Matt Schaub. ... Rookie cornerback T.J. Carrie, a seventh-round pick in May, intercepted a Schaub pass and returned it for a touchdown.
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