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Steelers fullback Derek Watt is out for the remainder of Pittsburgh's "Monday Night Football" game against the Bengals after suffering a blow to the head on special teams. Watt, who sustained the injury during the first quarter, is being evaluated for a concussion. 

Watt, the middle brother of NFL stars T.J. and J.J. Watt, endured a knee to his head after making the tackle of Bengals' return man Alex Erickson. Watt remained down on the field for several moments before leaving the field under his own power. Watt then went into the team's medical tent before heading to the Steelers' locker room. 

Like his brothers, Watt attended the University of Wisconsin, averaging 5.0 yards per carry during his senior season. He also spent three seasons in Madison blocking for Melvin Gordon, who later became his teammate with the Chargers.

Derek's brother, J.J., obviously watching his younger brother play on Monday night, took to Twitter to respond to fans' well wishes.

A sixth round pick in the 2016 draft, Watt helped Gordon become one of the NFL's best running backs during their four seasons together with the Chargers. After rushing for just 641 yards as a rookie (the season before Watt joined the Chargers), Gordon averaged nearly 1,000 rushing yards per season from 2016-17. Gordon also saw his yards per carry average climb from 3.5 to 4.1 yards with Watt as his teammate.

Watt is currently in the first of a two-year contract he signed with the Steelers back in March.