Paul Hewitt turned away from the on-court celebration, stared into the crowd, shook his head and flashed a look that was more befuddlement and relief than happiness.

His starting point guard, Bryon Allen, had just made a tiebreaking layup with two-tenths of a second left Saturday, a moment worthy of good spirits. Allen had been fouled on the decisive sequence and added the free throw, lifting George Mason to a 48-45 victory over winless Boston University in front of 4,375 at Patriot Center.

But as pleased as Hewitt was with Allen’s three-point play, which capped a 9-0 surge, he was troubled by his team’s sluggish performance — one that probably didn’t deserve to end in triumph.

“Every once in a while, you come around a team that doesn’t understand just how good they can be. This is one of those teams,” he said. “It’s [the coaching staff’s] job to get them out of it.

“We’ve got a really good basketball team. We’ve got all the pieces, all the parts, but we have our mental lapses. We just don’t do the little things we need to do all the time.”

The Patriots (4-2) have defeated Virginia and should have beaten New Mexico, but labored against Mercer and BU (0-5). They did win for the 31st time in 32 home games over two-plus seasons and restricted the Terriers to 28.3 percent shooting.

But they never led by more than four, committed 16 turnovers and made 2 of 16 three-pointers. They failed to sustain a rhythm and, over an eight-minute stretch of the second half, made one field goal.

“We are not playing to our best potential,” Allen said. “Most teams have bad nights — we’re all human — but for us to be as successful as we want to be, we have to come out and play better than that.”

The Patriots trailed by six with 3½ minutes left after conceding an 11-2 run. Marko Gujanicic completed a messy possession with a layup and Allen made a short jumper to cut the deficit to two.

After both teams missed, Gujanicic converted a pair of free throws with 42 seconds remaining to tie it. He had entered the game 1 of 9 from the line.

On the ensuing possession, the Terriers committed their 16th turnover when Maurice Watson Jr. stepped out of bounds with 14 seconds left.

Allen brought the ball upcourt and made an assertive move with about six seconds to go. Sherrod Wright set one screen. Johnny Williams set another. Allen slid into the lane, spun past a defender and flipped the ball in as he drew a foul.

“I was just trying to penetrate and hope I find something,” said Allen, who made a tiebreaking three-pointer with 62 seconds left in a 63-59 victory over Virginia two weeks ago. “I was looking [to pass], but once I did the spin move, I saw nobody near me.”

Allen finished with 7 points, 5 rebounds, 5 assists and no turnovers. Williams had 10 points and eight rebounds, and Wright added nine and nine for the Patriots, who shot 36.4 percent overall and needed more than 11 minutes to reach eclipse 10 points during an unsightly first half.

The Terriers, who had lost by two at Rutgers in their previous outing, made only six field goals before intermission — and four were three-pointers. BU’s Travis Robinson (17 points) made 3 of 4 from long distance before the break and added another to start the second half.

“We came out lackluster,” Williams said. “We should have been ready.”