Binocular was made to pull out all the stops to defend his crown in a thrilling williamhill.com Christmas Hurdle at Kempton.
Nicky Henderson's seven-year-old had ground to make up with Overturn on last month's running of the Fighting Fifth Hurdle at Newcastle, but market confidence saw him sent off the 5-4 favourite.
With Overturn adopting his customary front-running tactics, Tony McCoy on Binocular and Ruby Walsh on the progressive Rock On Ruby stalked his every move.
For a brief moment rounding the turn for home, it looked as though Overturn was beginning to get the measure of his opponents, but he gave way in the straight.
It quickly turned into a match and there was little between Binocular and Rock On Ruby jumping the final flight, but to his credit Binocular knuckled down well when it mattered to edge the argument by a neck.
McCoy said: "It was great he won and full credit to Rock On Ruby as he's an improving horse and took it up to him.
"It was brilliant he won, but I just feel he's a long way off the horse that won the Champion Hurdle. He's got plenty of issues and problems and whether it's stopping him from fulfilling his real potential I don't know.
"He's inclined not to race as keenly as he did before, but I was just disappointed he wasn't giving me the same feel he has in the past."
Henderson said: "He's still got a bit to find, even though he has done it well and I am chuffed to bits with him.
"AP (McCoy) said, he was half hoping the horse would be off the bridle going down the back because they would go so quick and that is the way it turned out.
"When he really does jump he is terrific and he winged the last, although it took him time to get there. Fair play to him, he has beaten Overturn far enough today but you have to keep piling the work into him so I still think there is room for improvement.
"I was talking to JP (McManus, owner) the other day and we really do want to campaign the horse this season.
"We might dodge the Sandown race (Contenders Hurdle) but I certainly hope to give him another run somewhere before the Champion Hurdle."
Paul Nicholls said of Rock On Ruby: "I just wish I could get him hurdling a bit more sharply, but it was still a great race.
"I think Cheltenham will suit him a bit better.
"I don't know what I'll do, whether I'll find another race somewhere, but I've got to find options for Zarkandar and Brampour too. Maybe we'll run all three (in the Champion)."
Beryl McCain, representing her son, Donald, said of Overturn: "He has run another cracker. I'm not sure what Donald will do with him but he might have a bit of a break now as he has been quite busy."