And that's why they call him "Slayer."

The Chargers mounted a historic victory over Pittsburgh in front of the entire country on Sunday Night Football, becoming the only team to ever come back from being down 16-plus points and defeat the Steelers on the road.

None of it would have been possible without Keenan Allen's monster performance in which he lived up to his "Slayer" moniker.

KA13 hauled in 14 passes on the night for 148 yards and one touchdown. It marked the second-most productive game of his career as he fell one reception shy of tying his team-record of 15 catches. 

In addition, he authored his 21st career 100-yard performance, tying Antonio Gates for the fifth-most in team history. The game marked Allen's fourth game since the start of 2017 with at least 10 receptions, 100 yards and a touchdown, tying for the most in the NFL over that span.

Allen's 14 catches also brought him to 406 for his career, moving into sixth place in team history. His touchdown catch was the 27th of his career, tying with WR Don Norton for the 12th-most touchdown receptions in Chargers history.

"He's one of the premier receivers in the game right now," Gates said bluntly in the locker room following the big win.

He certainly showed it on Sunday in a performance that left many of his teammates virtually speechless.

"Oh, my goodness," said Russell Okung. "Keenan's special, and when the game's on the line, the plays he's able to make are unbelievable. We see him do it in practice every day. The guy prepares like crazy. He's a football player, but he's one of the great ones."

"Crazy," Mike Williams added while shaking his head in disbelief. "It's crazy what he can do. All game he's just telling me, 'I'm killing them! I'm killing them, and they know it!' We all knew he was doing his thing out there today. He knows how to run a route like no one else."

Allen arrived at Heinz Field with an inkling he was about to put on a show.

He certainly did from the get-go, catching five passes for 55 yards over the first 15 minutes of the game.

"I was feeling a little comfortable (early)," Allen said with a wry smile when asked about his big day. "(It was) getting in tune with the game plan. Knowing what they were going to give us and then just me and Phil being on the same page."

His touchdown was also a memorable one as a pair of Steelers defensive backs collided into each other as the ball arrived, popping it into the air where KA13 ran under it for the score. A successful two-point conversion to Antonio Gates followed to make it a one-score game, cutting the Steelers lead to 23-15.

"Oh man, when he threw it, I'm like, 'Oh, Joe (Haden) made a play,'" Allen explained. "And then he got hit, I'm like, 'Oh I can make a play!' I was able to bring it down. I haven't (ever had a play like that)."

"It was still early, but it was kind of like, phew, we got away with one there," Rivers added. "I really liked it when I threw it. I thought it was going to be a give-me touchdown to Keenan. You know, that's a heck of a corner (in Haden). He's been a Pro Bowler for many years, and he undercut it and we got a lucky bounce. As my dad always said, 'The ball's not round.' The ball's not round and it bounces funny sometimes, and it bounced for us on that one."

Allen struck again a few minutes later following Desmond King's 73-yard punt return for a touchdown. The wideout broke free in the end zone, hauling in the pass from Rivers for the two-point conversion to tie the game.

Still, Allen's most important reception came on a play most fans likely overlooked.

However, Rivers made sure to emphasize how Allen's 12-yard catch-and-run on 3rd-and-4 from the Steelers' 34-yard line when tied 30-30 with 1:12 remaining was unequivocally the play of the game.

"Obviously, Keenan had an unbelievable day," Rivers said. "We had that 3rd-and-4 after (Austin) Ekeler got tackled out of bounds They still had one timeout, I knew that was the play of the game. I knew it was right there. I was like, we are too far out and we are going to have to punt if we don't get it. If we get, at the very worst, we are going to have (to kick) a field goal to win it. I don't know how far, but we are going to have (to kick) a field goal to win it, so that conversion was huge. (Allen) making the catch, I don't know how well it was thrown, but he came down with it."

Overall, while Sunday's win was a total team effort, there's no denying that Allen was a game-changing force for the Bolts.

"Keenan won his one-on-ones and he got open," said Head Coach Anthony Lynn. "He's a big target to fill. He's a heck of an athlete, and for Keenan to be such a big man, he can really change directions quickly. We just took advantage of the matchup."