Vikings linebacker Jason Trusnik might have to learn quickly this week.
Trusnik was signed on Tuesday and took part in his first practice Wednesday, replacing injured linebacker Audie Cole, placed on season-ending injured reserve with a fractured right ankle.
Also missing Wednesday, starting linebackers Anthony Barr (hand) and Eric Kendricks (ribs). Their availability for Sunday's game at Oakland is uncertain.
"I feel I have a good understanding of what they've been doing," said Trusnik, a nine-year veteran. "I can say that if they need me this week, I'll be ready."
Defensive tackle Sharrif Floyd, who has missed the past three games with knee and ankle injuries, and cornerback Terence Newman, who suffered a concussion against St.