FOXBOROUGH, Mass. -- Veteran defensive tackle Tommy Kelly was not spotted at the start of New England Patriots practice for the second consecutive day as he continues to deal with a knee injury suffered during Week 5.

Kelly is the team's top interior defensive lineman with nose tackle Vince Wilfork on injured reserve. On Wednesday, the Patriots signed defensive tackle Andre Neblett, perhaps as reinforcement in the event that Kelly cannot play this Sunday against the Saints.

In addition, top draft choice Jamie Collins was not spotted at the start of practice, conducted in shells, shoulder pads and helmets. The linebacker did practice Wednesday, but there is no word on the reason behind his absence Thursday.

Defensive end Michael Buchanan (non-injury related) returned to practice, while running back Leon Washington (ankle) missed his second straight day of on-field work.

Tight end Rob Gronkowski, who is expected to meet with the media later Thursday, was on the practice field, as has been the case throughout the season.