 Complete the following phrase:  In 1988 he defeated John Campbell, Stephen Hendry and Tony Knowles to reach his fourth World Championship semi-final. He played Terry Griffiths and, trailing 1113, lost a tied frame on a respotted black. Griffiths went on to reach the final courtesy of a 1611 win. White did at least manage to consolidate his number-2 world ranking. However the 198889 season was less successful, and Whites ranking slipped. He trailed John Virgo 1112 in the second round of the 