Arizona (6-0) struggled against Southern Miss' zone defense, throwing passes into traffic, to open spaces, even one that sailed over the coaches on the bench into the crowd.
The Wildcats survived behind their defense, forcing Southern Miss into 17 second-half turnovers to pull away to their best start since opening the 1999-2000 season with six straight wins.
Southern Miss (6-2) used its swarming zone while building an eight-point halftime lead and kept forcing Arizona into mistakes.
The Golden Eagles struggled against Arizona's pressure in the second half, though, missing all eight of their 3-point attempts while nearly quadrupling their turnovers from the first half.
Neil Watson led Southern Miss with 17 points.
The Wildcats rolled through the early part of their schedule, winning every game but one by double digits—the other was by nine—while ranking fifth nationally shooting at 52.3 percent and sixth in scoring at 85.2 points per game.
Arizona easily passed its first road test on Saturday, blowing out Texas Tech 85-57 in Lubbock behind Johnson's 18 points.
Defense has been the key to Southern Miss' strong start in its first season under coach Donnie Tyndall.
The Golden Eagles have yet to give up 70 points and are holding opponents 38 percent shooting, including 28 percent from 3-point range.
Southern Miss came to the desert off its first loss of the season, allowing New Mexico State to shoot 56 percent in a 68-60 loss on Saturday.
The clash of strengths went to the Golden Eagles early.
Southern Miss' quick-moving zone gave the Wildcats fits from the start, resulting in three turnovers—two on offensive fouls by Kaleb Tarczewski—two missed shots in three attempts and a pair of clanked free throws by Mark Lyons in the opening 5 minutes.
Even after coach Sean Miller called a timeout shaking his head in disgust, Arizona didn't get a whole lot better, missing four shots with three more turnovers to fall behind 10-3.
The trend continued the rest of the half.
Arizona went more than five minutes without a field goal and made 7 of 20 shots in the half, including 4 of 13 from 3-point range. What really hurt the Wildcats were turnovers; they had 13—two fewer than the entire game against Texas Tech—most on passes that had little chance of being completed.
Southern Miss wasn't exactly sharp offensively until hitting a few shots late in the half, including Cedric Jenkins' off-balance 3-pointer at the shot clock buzzer, but turned Arizona's turnovers into 18 points for a 35-27 lead.
Arizona turned the turnover table around in the second half.
Johnson, who hit a 3-pointer at the halftime buzzer, snapped the McKale Center to life with a steal and a breakaway dunk, then passed to Tarczewski for a dunk after the Golden Eagles stepped over the line on the inbound play for another turnover.
Southern Miss continued to struggle against Arizona's pressure, turning it over 11 times in the first eight minutes—eight on consecutive possessions—as the Wildcats raced to a 49-44 lead.
The Golden Eagles fought back to tie it, but Parrom scored on a pair of shots inside, then hit a 3-pointer in transition to put Arizona up 54-51. Solomon Hill followed with a 3-pointer and Arizona held Southern Miss off down the stretch for its most difficult win of the season.