CHAPEL HILL, N.C. — North Carolina just keeps winning, even if the past two performances haven’t been what coach Roy Williams wanted to see.For the 14th-ranked Tar Heels, the question is whether two straight close wins against teams from the bottom third of the Atlantic Coast Conference standings is a concern or just a blip headed into Saturday’s finale against their fiercest rival.James Michael McAdoo hit the go-ahead shot in the lane with 3:09 left and Marcus Paige blocked Eric Atkins’ driving shot on the final play to seal UNC’s 63-61 victory over Notre Dame on Monday night, earning the Tar Heels their 12th straight victory in their last home game.While the Tar Heels (23-7, 13-4 ACC) have their longest winning streak since 2008-09, it marked the second time in three days they found themselves in a fight with an underdog opponent. They won 60-56 at last-place Virginia Tech on Saturday, then blew a 14-point halftime lead and had to fight to the horn to beat the Fighting Irish (15-16, 6-12).“I said Saturday to have a really good year you’ve got to win some games ugly,” Williams said. “I’m tired of winning games ugly. ... I really thought we’d have a tremendous sense of urgency today.