Lazar Hayward added 17 points for the fifth-seeded Golden Eagles (24-8), who advanced to today's quarterfinals against fourth-seeded and 10th-ranked Villanova.
It was the first Marquette win since the loss of starting point guard Dominic James to a broken left foot. The Golden Eagles needed him in the four losses -- all to ranked teams -- but they didn't need him in the rout of St. John's, their ninth consecutive win over the Red Storm, a streak that dates to 1966.
James sat on the first seat of the bench in a warmup suit, his crutches next to him.
Paris Horne had 15 points for the Red Storm (16-17), who advanced to the second round with a 64-59 victory over Georgetown. The last time St. John's won two games in a Big East tournament was 2000 when the Red Storm won the third of their three titles.
St. John's had three field goals in the first half and the third, a banked rebound jumper by Justin Burrell with 1:28 left, made it 31-10 and brought a sarcastic cheer from the crowd at Madison Square Garden.
Marquette then closed the half on a 7-0 run for a 38-10 lead.
The 10 points were the fewest ever in a half in a Big East Tournament game breaking the 14 scored by Georgetown against Seton Hall in 2001, a 58-40 loss for the Hoyas. It was the fewest St. John's scored in a half since it managed 10 against Duke on Feb. 25, 2007. The Red Storm trailed by 24 at the half of that 67-50 loss.
ROBERT MORRIS 48, MOUNT ST. MARY'S 46
In Coraopolis, Pa., Robert Morris overcame an apparent home-court jinx to get back to the NCAA Tournament for the first time in 17 years, thanks to a late shot by a player who hadn't made a shot all night.
Dallas Green picked up a loose ball and made a hurried shot with 2.5 seconds remaining and regular-season champ Robert Morris beat Mount St. Mary's in the Northeast Conference championship game.
Jeremy Chappell scored 15 points as Robert Morris (24-10), rallying from five points down in the second half.
LEHIGH 64, LAFAYETTE 56
In Bethlehem, Pa., Alex Ross hit six 3-pointers and scored 21 points to lead Lehigh to its first Patriot League title in 12 years.
The Mountain Hawks (26-6) are heading to only their second NCAA Tournament and first since 1997 when they also beat Lafayette in the title game. Ross helped Lehigh avoid becoming Lafayette's third consecutive upset victim by sinking all six 3s in the first half to build a double-digit lead that was sliced to one in the final minutes.
Lafayette (10-22) upset No. 2 seed American and sixth-seeded Navy to reach its first title game in 12 years.