Selby lost the top ranking position to O'Sullivan on 24 March 2019, having been world number one since February 2015. O'Sullivan reclaimed the top spot by winning his 36th ranking title at the Tour Championship; Selby had himself been eliminated in the first round by Neil Robertson in a final-frame decider, after squandering a four-frame lead. He had an opportunity to regain the top spot at the China Open less than two weeks later, but lost 3–6 to Craig Steadman in the qualifying round which had been held over from the original qualification stage in February. At the World Championship, Selby beat Zhao Xintong 10–7 in the first round before being defeated 10–13 by Gary Wilson in the second round. As a result of this mediocre performance, he ended the season as world number six, having also been outranked by John Higgins, Neil Robertson, Mark Williams and Judd Trump.