Lorenzi won the first set and got an early break in the second, but the 57th-ranked Carreno Busta then won six straight games to level. The Italian broke again in the third set and led 5-3 before his Spanish opponent rallied to win the match.
''It was one of the best matches I have ever played,'' the 17-year-old Coric said. ''I still don't know what happened, I served so well.''
Fabio Fognini is the top-seeded player, followed by Tommy Robredo and Marin Cilic. All have first-round byes.