HIDALGO -- The defending NBA Development League champion Rio Grande Valley Vipers assured themselves of at least the number three seed in the playoffs with a 122-103 victory over the Springfield Armor on Saturday at State Farm Arena in front of a their third-straight sellout crowd, this time of 5,717.

If the Reno Bighorns lose at Bakersfield tonight, the Vipers will clinch the number two seed and their second-straight Western Conference Championship.

The Vipers (33-17) also set a new franchise record in attendance with a league-best 116,372, for an average of 4,849 per game. Last season the Vipers welcomed a league-best 113,077 fans through the doors during the regular season, an average of 4,712 per game.

The Vipers hit 15-of-23 shots (65.2%) in the first quarter, including 6-of-9 from behind the arc to take a 36-25 lead. Connor Atchley hit all three of his attempts from behind the arc while Matt Janning hit both of his.

The Vipers continued their hot shooting throughout the game shooting a season-best 60.5% for the game, including 48% (12-for-25) from behind the arc.

The Vipers took the largest lead of the game at 106-81 when Houston Rockets-assignee Hasheem Thabeet dunked a pass from Jerel McNeal with 8:25 remaining in the fourth quarter.

McNeal led all scorers with 26 points, hitting 11-of-16 shots while recording five rebounds, seven assists and four steals. Thabeet finished with 13 points, eight rebounds and three blocks. In total, eight Vipers reached double-figures in scoring, including Atchley (18), Mouhammad Faye (15), Jon Scheyer (15), Patrick Sullivan (12), Janning (10) and Richard Roby (10).

The Armor (13-37) were led in scoring by Philadelphia 76ers-assignee, who scored 24 points with eight rebounds.

The Vipers open up the best of three NBA Development League Quarterfinals on the road. Dates, times and opponents are expected to be available on Sunday.