BROOKLYN, N.Y. — On Monday George Washington coach Mike Lonergan called Chaz Williams of Massachusetts the fastest player in the Atlantic-10, warning that the 5-foot-9 junior could dominate a game with his quick hands and feet.

Thursday in the A-10 tournament opener at Barclays Center, Williams had even an extra spring in his step. He was playing in his hometown.

Guiding an offense that saved its best for last, Williams scored 16 points and dished eight assists propelling U-Mass to a 77-72 come-from-behind victory over GW before 5,751 in Brooklyn.

In the final 3:18, Williams made three layups, passed to freshman Trey Davis (14 points) for a pair of 3-pointers, and made the game-sealing steal as No. 6 U-Mass (20-10) advanced to a quarterfinal matchup with No. 3 Temple (23-8).

It was a big night for Williams, a transfer from Hofstra, who was playing three miles from his alma mater, Bishop Ford High. Two of his biggest fans – his daughter and grandmother — were in the stands.

“Nobody wants to come in here and lose the first night,” Williams said. “I guess I was a little too anxious in the beginning. But then I settled down and got all the jitters out.”

Williams’ performance spoiled a night in which GW (13-17) dominated inside behind senior Isaiah Armwood (16 points, 13 rebounds) and freshman Kevin Larsen (17 points, seven rebounds). The Colonials out-rebounded the Minutemen 50-32 with senior Dwayne Smith (six points, six rebounds) contributing to the show of force.

When Larsen scored on back-to-back possessions, GW grabbed a 66-61 lead with less than four minutes left. But U-Mass answered with 16 points on its final seven possessions. Williams touched off the rally by penetrating and dishing to Davis for back-to-back 3-pointers.

“Chaz was getting by us a lot,” Lonergan said. “Give them credit. We didn’t get stops when we needed to.”

Freshman Joe McDonald (10 points, four steals) gave GW its last lead, 72-71, hitting a baseline jumper with 1:24 left. But U-Mass spread it out and Williams barreled to the hoop for a pair of layups sandwiched around a Larsen miss to put U-Mass up 75-72. After Armwood missed GW’s eighth 3-point attempt of the night (without a make), freshman Patricio Garino chased down the rebound in the corner but was stripped from behind by Williams, ending the hopes of the Colonials.

It was the 18th turnover of the night for GW, which was often plagued this season by ball-handling woes.

“Some of that is youth and experience,” Lonergan said. “But a lot of that [Thursday] was Chaz just turning the heat up.”

It was a season of progression for GW. The Colonials started four freshmen, but weren’t content to take baby steps. They had flaws but compensated with discipline, effort, and cohesion. After Thursday’s loss, Lonergan sounded anxious for next year.

“We’re probably just a couple players away from being a pretty good team,” Lonergan said. “We can address scoring and shooting. We still kind of need a go-to player.”

As Lonergan said it, his thoughts drifted to Williams, clearly the difference between the teams on Thursday.

“Man, when that game was on the line, the last few minutes, I really thought he took over,” Lonergan said. “He’s a terrific guard. We just gotta find a guy like that.”