North Carolina's Williams: 'We got really lucky'

North Carolina head coach Roy Williams refused to be complacent after Sunday's victory over Arkansas.

The top-seeded Tar Heels closed out the game on a 12-0 run, emerging with a 72-65 win.

Williams wasn't thrilled about his team's performance, however.

"We were in the most difficult fight we've had all year long," Williams said to Lewis Johnson of CBS. "We got really lucky."

The Tar Heels advanced despite shooting 38.1 percent from the field, an issue Williams will surely look to address ahead of the Sweet 16.

North Carolina plays fourth-seeded Butler on Friday.