NEW YORK -- Justin Kier scored 26 points to help fifth-seeded George Mason slip past 12th-seeded George Washington, 61-57, in the second round of the Atlantic 10 tournament on Thursday.

Otis Livingston II added 12 points for the Patriots (18-14).

George Mason will meet fourth-seeded St. Bonaventure in a quarterfinal game Friday. The teams split the regular season series, with each team winning on its home court.

The third matchup of the season between the programs -- George Mason won the series opener, 62-55 on Jan. 26, and took the second game, 81-65, on Mar. 9 -- was a taut affair from the opening tipoff. Mason's biggest lead was eight points, early in the first half, while the Colonials had a five point lead in the second half.

Armel Potter led George Washington (9-24) with 12 points. Justin Mazzulla finished with 10.

Trailing by two, 54-52, following Javier Langarica's two-handed jam, Livingston II responded first with a 3, then knocked down a jumper to put George Mason ahead by 57-54.

Javon Greene made two free throws to push the lead to 59-54.

Langarcia's dunk occurred with 3:22 left. The Colonials did not score again until Terry Nolan Jr.'s right side 3 with three seconds left cut the Patriots' lead to two, 59-57. But Jamal Hartwell II's drilled two free throws with two seconds left to seal the win.