COLORADO SPRINGS, Colo. -- The New England Patriots' running back position has officially been turned upside down.

Mike Gillislee opened the season as the top candidate to replace LeGarrette Blount, a role he held through the first five games, but now he’s not even a certainty to be active on game day. A combination of Dion Lewis and Rex Burkhead has taken over as the top rushers, complementing passing back James White, and there’s little reason to think that won’t continue to be the case Sunday against the Oakland Raiders in Mexico City (4:25 p.m. ET, CBS).

For his part, Lewis welcomes the increased workload and said he feels good physically. That has sometimes been the concern with the 5-foot-8, 195-pound dynamic threat: With more work comes a greater injury risk.

But one of his mottoes has been, “I’m small, but I’m not little," which is basically his way of saying not to judge him by his size.

“I’m strong, and I don’t go down easy,” he explained. “So I don’t like to be called [little].”

Lewis’ production has been big ever since the coaching staff elevated him to a starting role Oct. 15 against the Jets, as he once again looks like the player he was before tearing his ACL in November 2015.

Lewis has averaged 26.5 offensive snaps in the past four contests after having been limited to an average of 12.8 through the first five games. Add in his responsibilities as the primary kickoff returner (103-yard TD on Sunday) and his spot on the game-day roster is as secure as it has ever been.

Then there’s the 5-foot-10, 210-pound Burkhead, who is a true dual threat as a pass-catcher and rusher, and also plays on the punt-rush/return unit as well as the kickoff-coverage unit. Like Lewis, his snaps have been rising the past three weeks -- 13, 27 and 36 -- since returning from an injury to his ribs. He gives the Patriots an element of versatility and unpredictability on each play.

“Whatever the coaches see fit, whatever role they want to put me in and gives our team the best chance to win, I’m more than happy to do that,” he said.

Because Lewis and Burkhead have combined effective running with vital roles on special teams, and White is invaluable on third down, Gillislee is now fighting just to find a spot on the 46-man game-day roster. Gillislee doesn’t factor into the top special-teams mix, which hurts his cause.

Now that the team has four tight ends after claiming Martellus Bennett on waivers, there's another obstacle in Gillislee’s path.

Gillislee, who was a healthy scratch in Sunday’s victory over the Broncos after averaging 13 snaps per contest over the three games before that, declined interview requests Thursday at the Air Force Academy.

That left the media spotlight to Lewis and Burkhead, which is the way it has been on the field as well.