Rory McIlroy ahead of the 2019 Sentry Tournament of Champions on the Plantation Course at Kapalua in Lahaina, Hawaii. (Stan Badz/PGA TOUR)

1. McIlroy threatens to quit European Tour

European Tour CEO Keith Pelley had to scramble to Northern Ireland to talk his most prized asset into coming back to the European fold when McIlroy threatened to quit the Tour after the 2018 season, saying he would concentrate solely on the PGA Tour in 2019. The Northern Irishman delayed renewing his membership until April and eventually rejoined the Tour. The story generated huge headlines.