John Calipari is heading to the Sweet 16 for the 16th time, guiding the Arkansas Razorbacks past nemesis Rick Pitino and second-seeded St. John’s 75-66 on Saturday to bring his fourth school to the NCAA Tournament’s second week.

Billy Richmond III scored 16 points and Karter Knox had 15 for the 10th-seeded Razorbacks, who sent Kansas and their Hall of Fame coach Bill Self home from the “Region of Coaches” in the first round.

But the victory over his longtime rival was especially sweet for Calipari.

Zuby Ejiofor had 23 points and 12 rebounds for Big East champion St. John’s (31-5) — an unprecedented sixth school Pitino has taken to the tournament. His history in Providence — the Friars reached the 1987 Final Four in his tenure — gave him a home-court advantage.

But in a poor-shooting foulfest, Arkansas (22-13) barely did enough to eliminate St. John’s — making the Red Storm the first team seeded No. 4 or higher to exit what’s been a chalky tournament so far.

The teams combined to make four 3-pointers on 41 attempts, with St. John’s shooting 28% from the floor overall. After cutting an eight-point lead with eight minutes left to two, 62-60, the Red Storm missed their last seven 3-point attempts.