O`BRIEN SET TO LAUNCH ISTABRAQ Istabraq is likely to begin his quest for a fourth successive Champion Hurdle triumph when he reappears at Leopardstown next Friday.Aidan O`Brien`s superstar is among 14 entries for the A.I.B. Agri-Business December Festival Hurdle at Leopardstown next Friday, a race he won last year.The eight-year-old was last seen in public in the Smurfit-sponsored prize at Cheltenham back in March when he defeated Hors La Loi III by four lengths to become only the fifth horse to win the hurdling crown three times.However, his participation had been in doubt until two hours before the race as he was found to have a bloody nose the previous evening.Istabraq is 4-7 with Ladbrokes for the 2001 Champion Hurdle.Theatreworld, runner-up in the 1997, 1998 and 1999 Champion Hurdles, is O`Brien`s only other entry in the IR#19,500 event over two miles.Other possibles for the Leopardstown feature include Stage Affair, Nomadic, Moscow Flyer and Mantles Prince.The four-day Leopardstown Festival opens on Tuesday with a field of six declared for the main event, the IR#39,000 Denny Gold Medal Novice Chase.The sextet includes Michael O`Brien`s Knife Edge, who made an impressive chasing debut at Naas last month, Arthur Moore`s Well Ridden, a promising third to Sackville at Fairyhouse three weeks ago, and former smart hurdler Balla Sola from the Willie Mullins yard.