Richard Johnson was banned for seven days and fined £6,550 after being found guilty of misusing his whip during the course of his Timico Cheltenham Gold Cup victory aboard Native River.
The Colin Tizzard-trained victor was involved in a prolonged duel with Might Bite in the three-and-a-quarter-mile feature, with Native River eventually coming home four and a half lengths clear.
However, the stewards found Johnson had used his whip above the permitted level from approaching the second-last fence, prompting the lengthy suspension and sizeable fine, which is proportional to the £369,821 first prize
After passing the winning post, Johnson said: "I'm speechless. He's been a fantastic horse for me and I was lucky to pick up the ride on him.
"He's just amazing. He jumps for fun. I was getting squeezed, but at the second-last and the last he just wanted it so much.
"I knew Nico (de Boinville, on Might Bite) was there and to be fair to Might Bite, he's run a hell of race, but I think we just outstayed him. They are two very brave horses."
He added: "Eighteen years (since Looks Like Trouble) seems a long time!"