 Nyorai kuenderera mberi kweiyi ndima - OSullivan akatanga mwaka wa1998-1999 nekukunda maScottish Masters asina chinzvimbo, asi akaenderera mberi nekukunda mamwe mazita mumwaka. PaUK Championship, OSullivan ndiye akanga achidzivirira mukwikwidzi, asi akabva mumutambo uyu nguva pfupi asati atarisana nemutambo wake wekutanga. Maneja wake akataura kuti akanga achitambura nokuneta kwomuviri nokwemirangariro uye kuti chiremba wake akanga arayira zororo rakakwana kubva mu snooker. Mishumo yakazotevera yakataura panzvimbo pezvo kuti akanga achitambura nokuora mwoyo panguva iyoyo. Mumakwikwi ekupedzisira ekupedzisira kweWelsh Open, OSullivan akaita chechipiri chikuru chebasa rake rehunyanzvi, achitamba naJames Wattana. OSullivan akasvika kumaquarter-fainari eMasters, asi akarasikirwa ne2x6 kuna Ken Doherty. Mumutambo wake wechina wokupedzisira muCharity Challenge, uye mukudzokorora mugumisiro wegore rapera: OSullivan akarasikirwa naJohn Higgins zvakare, nguva ino 49. Mumakwikwi Enyika, OSullivan akasvika muchikamu chake chechitatu chokupedzisira mumakore mana. Asi, akarambidzwa zvakare nzvimbo mumutambo wekupedzisira paakarasikirwa 1317 naStephen Hendry mumutambo wemhando yepamusoro uyo waive nezvikamu zvemazana emakore mune mafuremu mana akateedzana maviri naOSullivan e134 ne110, achiwana 134 nekuda kwekushaya pink yekuputsa kwakanyanya. 