O'Sullivan began the 2004–05 season by winning the Grand Prix, defeating Ian McCulloch 9–5 in the final. He then reached the semi-finals of the British Open, losing 1–6 to Stephen Maguire, and the last 32 of the UK Championship, losing 6–9, once again against Maguire. In 2005, O'Sullivan defended his Welsh Open title, by defeating Stephen Hendry 9–8. During the tournament, O'Sullivan compiled ten century breaks, including a break of 146, the highest of the tournament. After this, he won his second Masters title, by defeating John Higgins 10–3. After the final, Higgins described O'Sullivan as a "total genius" because of ten breaks over 50 in the final including three centuries.