During the
Grand Prix era of the tournament, it has trialled several knockout formats. The tournament had a flatter structure than most tournaments back in the 1980s, with the top 32 players all coming in at the last-64 stage. Although now being the standard knockout format for ranking snooker events, there used to be only 16 players left when the players ranked 17–32 came in, and then the 16 winners of those matches faced the top 16; this structure is now only used for the
World Championships. These facts made it more common to see surprise results than in most other tournaments, with players such as
Dominic Dale,
Marco Fu,
Euan Henderson and
Dave Harold all surprise finalists at the time; players from outside the top 16 have reached the final roughly half the times the contest has been played. Many top 16 players were eliminated in the early stages of the contest; taking the
1996 event as an extreme case, thirteen of the top sixteen seeds failed to reach the quarter-final stages, and the semi-finals featured one match between two top-16 players (Mark Williams and
John Parrott) and another between two unseeded players (Euan Henderson and
Mark Bennett); with Bennett and Henderson respectively winning the first two quarter-final matches, a surprise finalist was guaranteed before the quarter-finals had been completed.
Round-robin era The event was played in a brand-new
round-robin format in 2006, more similar to
association football and
rugby tournaments than the knockout systems usually played in snooker. Players were split into groups (8 groups of 8 in qualifying, 8 groups of 6 in the final stages) and played every other player in their group once. The top 2 players progressed; the last 16 and onwards were played as a straight knockout. This resulted in several surprise results. Little-known players such as
Ben Woollaston,
Jamie Jones and
Issara Kachaiwong made it through qualifying, while stars such as
Graeme Dott,
Stephen Hendry and
Shaun Murphy failed to clear their groups. The format was slightly tweaked for
2007, after complaints (notably from
Dennis Taylor) that the system was too random. Matches increased in length from best-of-5 to best-of-7, to give the better player more chance to win. The main tie-breaker for players level on wins was changed, with frame difference now taking precedence over results between the players who are level on points. Notably, under the 2007 format, 2006 runner-up
Jamie Cope would have been eliminated in the groups, for he defeated third-placed
Michael Holt but had an inferior frame difference. The 2007 event saw fewer surprises, although 2006 world champion Graeme Dott, 1997 world champion
Ken Doherty, defending champion
Neil Robertson, seven-time world champion Stephen Hendry, six-time world champion
Steve Davis, twice world champion Mark Williams and 2007 World Championship finalist
Mark Selby were all eliminated in the groups. The format was not continued for 2008 due to dwindling ticket sales in the early rounds.
FA Cup-style draw and reversal The
2008 event went back to a knockout format with no round-robin; however, the last 16 and beyond were played using an
FA Cup-style draw, rather than automatically pitching higher-ranked players (or their conquerors) against lower-ranked players. Following
Barry Hearn's takeover of the
WPBSA, it was returned to its original format, where amateurs had to win 3 matches to qualify for the main draw. ==Winners==