Mickey McConnell hit five three-pointers and finished with 23 points, while Clint Steindl made 3-of-5 from beyond the arc and donated 11 points for Saint Mary's (27-5), which earned the 10th seed in the South Region and will meet second-seeded Villanova in the second round on Saturday. The Wildcats escaped with a 73-70 overtime win against No. 15 seed Robert Morris earlier on Thursday.
The Gaels improved to 2-5 all-time in the tourney with their other win coming back in 1959 against Idaho.
David Gonzalvez had a team-best 18 points for Richmond (26-9), which came into the NCAA Tournament as the seventh seed in the South Region. The Spiders entered the tournament as the Atlantic 10 Conference runner-up after falling 56-52 to Temple in the championship game. Kevin Anderson and Ryan Butler ended with 16 and 14 points, respectively.
The Spiders' 26 victories this season tied a school record.
Tied at 36-all at the half, St. Mary's went up 50-42 following a three-pointer by Steindl with 13:50 to play in the second. The Gaels' lead swelled to 15, 65-50, after Steindl finished off an 8-0 run with another triple with 7:32 remaining.
Richmond was only able to get to within nine, 74-65, with 2:29 left and never threatened the outcome the rest of the way.
In a back-and-forth first half, Butler's three-pointer put Richmond up by five, 24-19, with 9:06 remaining, and the lead reached six after Anderson hit a jumper with 4:33 to play in the stanza.
Dan Geriot's layup kept the Spiders in front 36-33 with 41 seconds left in the half, before McConnell's triple in the waning seconds tied things heading into the locker room.
This was only the second meeting between the two schools on the hardwood. The first matchup took place back in 1985 and the game was claimed by Richmond, as the Spiders defeated Saint Mary's, 75-63...The Gaels made 49.1 percent of their shots and 8-of-19 from three-point territory...Richmond shot 47.2 percent from the floor and 10-of-21 from beyond the arc.