Updated

The Oakland Raiders will have to deal with one of their toughest defensive tests without one of the leaders in their secondary.

Starting strong safety Tyvon Branch will likely miss significant time with a right ankle injury starting with next Monday night's game against Peyton Manning and the high-powered Denver Broncos.

Branch is one of two returning starters on a much-improved defense for Oakland (1-1) that leads the league with nine sacks and has allowed just three scores on its last 17 drives. Branch got hurt rushing the passer in the first quarter of Sunday's win over Jacksonville.

Coach Dennis Allen would not confirm an ESPN report Monday that Branch broke his leg but said Oakland's highest-paid player in 2013 will be out for "some time."