Trainer Paul Nicholls admitted his hand was forced into introducing the 11-year-old back into competition on heavy ground - after 14 months on the sidelines due to a tendon injury - as he continued his preparation for a fifth World Hurdle.
While former jockey Ruby Walsh would usually restrain Big Buck's until the final couple of flights, new pilot Sam Twiston-Davies boldly sent him on with more than a mile remaining. It was only on the run-in his exertions started to take their toll as he was passed by Knockara Beau and At Fishers Cross to hit the line in third, a short head and three-quarters of a length adrift.
Sent off the 6-5 favourite, the Andy Stewart-owned superstar was cut by World Hurdle sponsors Ladbrokes to 5-4 from 7-4 for his next assignment on March 15 and Nicholls was only positive afterwards, saying: "I'm delighted with him. He travelled with all his old zest and jumped well, but he just got a little tired.
"It's very testing ground and we could easily have taken him out and saved him for another day, but I was desperate to get a run into him before the World Hurdle. This was only the second time he'd been on grass since his injury. I wanted another racecourse gallop but the ground wouldn't allow it.
"That will improve him enormously. I'm thrilled, I would obviously have liked to have won, but that will put him bang on for his next run. I said to Sam to be positive on him and if he got tired, he got tired."
Twiston-Davies said: "I rode him as if he was 150%ready and he just got tired in the last 150 yards, which is fair enough as he has been off for more than a year. Most of the others had the benefit of a couple of runs.
"He has always been ridden handy and he jumped brilliantly. It was a real buzz for me, and I promise you when he takes them on again in the World Hurdle he'll run a massive race. He felt very special, as we all know he is." Owner Stewart said: "Perhaps it was lack of fitness, or age has got to him, but we'll definitely be there on the Thursday [of the Festival]."
When Twiston-Davies took the bull by the horns on the back straight, he initially had his rivals toiling but turning for home they had managed to regroup and Boston Bob, Reve De Sivola and At Fishers Cross all scented victory.
Knockara Beau, who is the same age as Big Buck's but invariably discounted despite five placed efforts from 15 previous tries at the course, made his own unexpected play for glory and wrestled the lead from the champ- ion with 50 yards remaining.
Winning jockey Jan Faltejsek said: "He has run some amazing races at Cheltenham and always just missed out, but he's finally won and I'm over the moon. In the past he has made little mistakes that have cost him so hopefully he has learned his lesson."
Knockara Beau's trainer, Northumberland-based George Charlton, said: "Even if he makes mistakes, he always goes well up that last hill, and you wish the winning line was at the top! We were fairly worried about the ground, but he'd had a little wind operation. He's been dropping his soft palate, he was hitting the fence coming down the hill.
"He had it done about three years ago and we've just had it done again. The plan was to go for the Kelso race which he'll have 12st in next month but I've put him into the Gold Cup and I might just run him."
At Fishers Cross's jumping has not yet returned to last season's fluency but this was step in the right direction. Trainer Rebecca Curtis said: "It seems like he's getting back to where he was last year. He's had a lot of physical problems, but that was a lot better and we can think about coming back here now."
David Bridgwater's faith in The Giant Bolster (6-1) was vindicated once again when the nine-year-old returned from a period in the wilderness to win the Argento Chase, finishing seven lengths clear of Hennessy runner-up and 6-4 favourite Rocky Creek.
The 6-1 chance reaped the benefit of first-time double headgear to have the Grade Two in the bag before the last.