PROVIDENCE, R.I. — Billy Richmond III scored nine of his 16 points in the second half, allowing 10th-seeded Arkansas to withstand a comeback from second-seeded St. John’s and earn a 75-66 victory in Saturday afternoon’s West Region second-round action.The Razorbacks (22-13), who are 5-1 in their last six games, advanced to the Sweet 16 for the fourth time in five years despite shooting just 2-of-19 from 3-point range and four players getting into foul trouble.In a legendary coaching matchup with Rick Pitino of St. John’s (31-5), John Calipari earned his 59th all-time NCAA Tournament win — the most among active coaches.Karter Knox (15 points) and Johnell Davis (13 points) were also double-figure scorers for Arkansas, which had a 13-point lead whittled down to two with 4:11 left in regulation.The Razorbacks will face either Texas Tech or Drake in the Sweet 16.Zuby Ejiofor had 23 points and 12 rebounds for St. John’s, but a 28 percent shooting night and just 2-of-22 from distance was too much to overcome.Leading scorer R.J. Luis Jr. was held to 3-of-17 shooting and had just nine points. Deivon Smith added 13 points.The Razorbacks scored the final seven points of the second half to take a 35-32 lead and never trailed from there. Zvonimir Ivisic’s inside finish flipped the score before Boogie Fland’s hanging layup in the paint capped the period.The momentum stayed after halftime as two D.J. Wagner layups — including a blow-by to force an early timeout — and a Knox transition layup fueled an opening 9-2 run.