Pittsburgh — During their second practice day, outside linebacker T.J. Watt gave the Pittsburgh Steelers cause for optimism by making progress in his concussion protocol recovery.

After being limited to the team’s opening practice of the week, Watt participated fully in the team’s second practice day. The progression should point to a nearer return, but before clearing protocol and playing against the Indianapolis Colts, he must still receive clearance from an outside neurologist.

As he works to recover from a concussion, Watt’s running companion Alex Highsmith continues to participate in practice to a limited extent. The day following their Week 14 loss to the New England Patriots, both players joined the protocol.

Initially diagnosed as having a neck injury, Highsmith left the game against New England during play. And the following morning, he went into protocol.

To play, both players must receive clearance before Saturday. In the event that neither player plays, rookie Nick Herbig is anticipated to start, and if Watt and Highsmith are not available, Markus Golden will also start.