Roy Williams told reporters that Bullock had been playing better than anyone on the team this season and described his junior wing's absence as a "pretty big blow."
His message to Hairston was clear: "You don't have to be anybody else, just be yourself."
It came as no surprise to the 20,888 in attendance at the Smith Center that Hairston fired up a 3-pointer on UNC's first possession. The defensive effort that followed, however, was enough to impress everyone watching.
"When I found out Reggie wasn't playing because of the concussion, it clicked for me that I had to step up," Hairston said. "Being that Reggie is one of the best defenders on the team, I knew I had to step up defensively and basically make up for Reggie being out."
Hairston notched a career high with four steals, drew a pair of charges and scored off both of his offensive rebounds to help set a defensive tone that frustrated UNLV throughout the first half. Those statistics reflect more on his quality play than do his 15 points and four rebounds, both of which were good for second-best on the team.
"I think he did some good things for us defensively," Williams said. "One time on the break, Brice [Johnson] didn't sprint back and [Anthony] Bennett's going right down the lane and they throw it to him and P.J. steps up and takes the charge. So he really did some good things."
Hairston also stepped up big down the stretch. He drained a 3-pointer from the top of the key out of a timeout after UNLV had cut UNC's lead to 57-56 with 10:06 to play.
With 28 seconds left to play, Hairston stepped to the free throw line and knocked down both shots to give the Tar Heels some breathing room at 78-73.
"We knew we weren't going to have Reggie yesterday, but just knowing that we've got somebody like P.J., who can step into his role and play just as good as Reggie can… he really helped us," sophomore forward James Michael McAdoo said. "We probably wouldn't have won the game if we didn't have his outside shooting and just his tenacious defense."
Senior guard Dexter Strickland also praised Hairston's play.
"Just his energy alone, his presence," Strickland said. "Being 6-5 and still being able to box out guys that are 6-9, 250. I'm so glad he's on our team."
Hairston didn't commit a single turnover in a career-high 32 minutes, nine more than his previous high of 23 minutes (UAB).
While Hairston's defense drew the bulk of the accolades on Saturday, his offense continued on its upward trend. The Greensboro, N.C. native is averaging 15.5 points over his last four games and 14.1 points over his last 10.