 Complete the following phrase:  Hat-tricks are more of a common occurrence in the group stages, as the match-ups usually place higher-ranked teams against lower-ranked teams. Just nine hat-tricks have occurred in the knockout stages, five happening in the quarter-finals and four in the semi-finals. They have been scored by Bryan Fletcher and Robbie Paul in the 2000 tournament, Billy Slater and Johnathan Thurston in the 2008 edition, Jarryd Hayne twice and Brett Morris in the 2013 competition and Valentine Holmes twice in the 