CHARLOTTE - Before Thursday's NCAA regional semifinal game at Charlotte Bobcats Arena, North Carolina basketball coach Roy Williams said he wrote three things on the locker room board:

Tough enough.

Patient enough.

Poised enough.

By proving they were all of those things on defense, the top-seeded Tar Heels beat No. 4-seeded Washington State 68-47. And by holding the Cougars to their lowest points total of the season -- and the fewest points a UNC opponent has scored in the NCAA Tournament since 1946 -- Carolina proved it is worthy enough to advance to Saturday's 9:05 p.m. regional final against No. 3 seed Louisville.

"We continue to talk about this throughout the year, that we're tired of hearing people say that North Carolina can't play defense, and that's going to be our weak link in our efforts to get to the Final Four,'' forward Marcus Ginyard said after UNC outrebounded WSU by 14 and held it to 31.6 percent shooting. "But tonight, I think you've seen that this team has the capability of buckling down and being that great defensive team ... that can make that run."

The Cougars (26-9) offered the ultimate test to UNC's defense: making the Tar Heels (35-2) stick for a full 35 seconds per possession.

WSU, second in the nation in points allowed (56.1 per game), tested UNC's focus early by chewing up the clock via power-walking the ball up the court, then being ultraselective with its shots. The methodical strategy had been the hallmark of the Cougars' 26 victories and first trip to the NCAA round of 16, but for it to keep working -- for them to keep Carolina from scoring in transition and running away with it -- the Cougars had to make shots.

And the Tar Heels made sure they didn't.

Sure, UNC trailed for the first time in this tournament when WSU center Aron Baynes opened the game with a dunk. The Heels committed eight first-half turnovers by rushing plays. And All-America forward Tyler Hansbrough, held without a field goal in the first half for only the second time this season, didn't score until he made two free throws 77 seconds before halftime.

But after Baynes cut the deficit to 15-14 with a dunk with 8:58 left in the first half, Carolina outscored the Cougars 20-7. UNC sixth-man Danny Green made up for Hansbrough's woes by scoring 12 of his 15 points before halftime, and he also helped his defense hold Washington State to two field goals during that roughly nine-minute span.

"They walk it up the court and they get it across the ... line with seven or eight seconds already elapsed,'' Williams said. "And they don't necessarily try to hold the ball down, but they try to hold the ball until they get exactly what they want.

"So I said to Marcus and Wayne [Ellington] and Danny, 'You're going to be hit by a screen, you've got to be tough enough and patient enough to get through it. And a guy's going to cut on the baseline, and he's going to stop and cut the other direction, and you've got to be tough enough and patient enough to continue trying to play the defense for 35 seconds.' "

And they were.

Carolina led 35-21 at halftime, and WSU never had a chance to make a dent. Not only did Hansbrough start connecting -- he finished with a game-high 18 points -- but the Tar Heels held the Cougars to 29 percent shooting in the second half.

In the end, WSU's leading scorers, Derrick Low and Kyle Weaver, were held to a combined 9-for-29. Baynes and Low led the Cougars with 14 points apiece.

"It was freezing out there," Weaver said of WSU's shooting. "I thought we got a lot of good looks offensively ... it just wouldn't go down for us tonight, even inside."

Ellington added 13 points for Carolina, which has won three straight NCAA games by 20 points or more for the first time.

The defensive performance comes at a good time. Saturday, the Heels will try to avenge last year's defensive letdown in the regional final, where they blew a double-digit lead and eventually lost to Georgetown in overtime.

"We still have a really bad taste in our mouth from what happened last year," Ellington said. "And now it's our job to get past this point."

Being tough enough, patient enough and poised enough -- particularly on defense, again -- should help.