World number one Ronnie O’Sullivan believes world champion John Higgins has underachieved in his career to date.

Higgins added a third world title to his haul earlier this year equalling the amount won by O’Sullivan – often regarded as the most talented player of his generation.

Higgins aims to retain his Grand Prix title in Glasgow next week – starting with a first round match against Mark Joyce.

But O’Sullivan said: “John is one of the all-time greats but I think he’s actually underachieved to date.

“It sounds like a strange thing to say but it’s because of how highly I rate him and I know some of the other players would agree.

“He’s the best tactical player ever – ahead of Steve Davis because he’s a heavy break-builder as well so he’s got no weaknesses.”