The Pittsburgh Steelers made T.J. Watt the highest-paid defensive player in the NFL before the season, and he delivered an emphatic reminder of why in their win over the Seattle Seahawks.

Pittsburgh moved to 3-3 on the year with a dramatic overtime triumph over the Seattle Seahawks on Sunday, with edge rusher Watt having a decisive say.

Watt was a constant thorn in the side of Seahawks backup quarterback Geno Smith, filling in for the injured Russell Wilson, and saved his biggest impact for overtime.

He sacked Smith for the first time in the extra period and did so again after the Steelers punted the ball back to Seattle, this time robbing him of possession in the process and giving Pittsburgh crucial field position deep in Seahawks territory.

That allowed Chris Boswell to hit a 37-yard game-winning field goal and clinch a 23-20 success.

Watt signed a four-year, $112million contract extension with $80m in guarantees back in September, a price Pittsburgh will be more than happy to pay if he maintains his stellar play.

"That's how he’s compensated," said head coach Mike Tomlin. "I don't think anyone is surprised by his ability to deliver in those moments."

His team-mate on the defensive front, Cameron Heyward, was certainly not shocked when Watt's pressure finally told in the most pivotal spot.

"I love the fourth quarter and the overtime by T.J.,” Heyward said. "All game, he was like, 'Man, I’m just not hitting home.' I told him it was going to come and just, 'Keep staying after it. You’re going to be great.'

"And when we needed it the most, he made his plays. What an emphatic play to end the game with a sack strip fumble. We needed it, and he's a hell of a player."