The England international could be out of action for any time between 10 days and six weeks with a broken toe.
"It's one of those challenges which comes along," the Liverpool Echo quotes Martinez as saying. "You don't want to change successful units and we've been very strong in the back four along with Tim Howard, but we've got options and I'd say we're in a healthy position to replace any position in the team.
"I'm looking at the level now of the players who have been very unfortunate not to be in the starting line-up so far. To see how they can show me what they can do. I don't see it as a negative, it's a challenge we're going to grasp with both hands."
The 28-year-old has played every minute of the Toffees' last 51 Premier League matches.