CHAPEL HILL — There likely is no turning back now. Roy Williams acknowledged that much Monday, one week after guard P.J. Hairston arrived at practice to find his name listed along with four others in North Carolina’s starting five.

Hairston’s presence in the starting lineup has made UNC a smaller team, but one more capable of scoring. The Tar Heels aren’t yet running the way Williams wants – and they haven’t all season – yet Hairston’s presence has made them appear quicker, too.

“We’ve done some things these last two games that have helped us,” Williams said two days after his team’s 93-81 victory against Virginia. “So we’re not going to go back to exactly like we were before, because I think during the course of the entire season you always see some things change with your team that will drive you in different directions.”

So the Tar Heels have been driven to go small, perhaps against Williams’ instinct. His most successful teams at UNC, after all, have been interior oriented, and they have relied on capable forwards and centers.

So far, though, going small has proven to be an advantageous move, though Williams understands it won’t be without challenges. One of them will come Tuesday night at Georgia Tech, which features a physically imposing frontcourt that at times won’t rely on a player shorter than 6-foot-8.

The Tar Heels’ starting frontcourt, meanwhile, will consist of 6-9 forward James Michael McAdoo and 6-5 Hairston. Joining them will be guards Marcus Paige, Dexter Strickland and Reggie Bullock – perimeter players. All have been given a mandate from Williams to play taller and tougher than their size.

As he did Saturday after the victory against Virginia, Williams didn’t offer specifics when asked what Hairston had done to merit an expanded role. After a loss at N.C. State, Williams had criticized Hairston’s hustle.

Hairston now has played more minutes in the past two games than he had during any other two games this season.

“A lot of it is too complicated to talk about,” Williams said. “… We decided to shorten our lineup a little bit, shorten the substitutions. We may go back and start playing 10, 11 guys in the first half like we did for a long time there if the matchups are different.

“But the last two games we’ve thought it’s been good matchups to stay small for a really, really long period of time.”

The tall Yellow Jackets’ frontcourt – with 7-foot center Daniel Miller, 6-8 forward Robert Carter and 6-9 reserve forward Kammeon Holsey – could test Williams’ commitment to his smaller lineup in ways Duke and Virginia didn’t during the Tar Heels’ past two games.

“It causes us problems,” Williams said. “But hopefully it causes them problems, as well. And I think you’ve got to go with what you feel more comfortable with at that time.

“But I think over 40 minutes it’s hard for P.J. to guard a 6-8, 6-9 guy for 40 minutes. We understand that part. But also it might be hard for them to guard him.”

Georgia Tech coach Brian Gregory acknowledged that potential problem. When UNC and Georgia Tech met at the Smith Center on Jan. 23, Gregory didn’t have to worry much about matching up with the Tar Heels’ small lineup.

UNC back then used a four-guard lineup, but only in short stretches. The Tar Heels didn’t use it often in their 79-63 victory against the Yellow Jackets, and Hairston played just 17 minutes in that game.

He played twice as many minutes in UNC’s loss at Duke last week, and 29 in the victory against Virginia.

“It’s a difficult matchup, and it is for just about anybody,” Gregory said of UNC’s four-guard lineup. “… You have to be able to defend on the perimeter. … Big guys have a tendency to keep getting stuck towards the rim when they are off the ball and if you do that, you’re going to give a wide open shot.”

Hairston, who made six of 12 3-point attempts Saturday, has done a good job lately of taking advantage of those.

Carter: 919-829-8944 Twitter: @_andrewcarter