Riders Onthe Storm won the Ascot Chase in a race which saw favourite Cyrname and Traffic Fluide fall.
Cyrname led in the latter stages but was overtaken by Riders Onthe Storm with two fences to go.
Traffic Fluide moved into second to challenge at the front but, along with Cyrname, fell at the last fence as Riders Onthe Storm went on to win.
Traffic Fluide was quickly on his feet and there was a huge cheer from the crowd when Cyrname eventually got up.
“He just got winded,” Cyrname’s trainer Paul Nicholls told ITV Sport.
“He’s fine. We’ll get him back. I’d say leave him until next season now.
“There is something missing, I can’t really put my finger on it but he’ll be back and that is the main thing.”
At Haydock, Smooth Stepper won the Grand National Trial Handicap Chase.
Smooth Stepper was the 33-1 outsider in a 10-strong field and beat long-time leader Lord Du Mesnil over an extended three and a half miles.
BBC horse racing correspondent Cornelius Lysaght
What was billed as potentially a dramatic day because of Storm Dennis turned out to be filled with a more traditional sort of drama.
In the Ascot Chase, Cyrname was showing that he’s not himself, falling heavily at the last fence when well beaten – what a relief that all was OK.
It’s impossible to say that Traffic Fluide wouldn’t have won if he hadn’t fallen separately at the same place.
In Haydock’s Grand National Trial, long-time leader Lord Du Mesnil did everything right but was overhauled late on by Smooth Stepper for which the race is likely to have been a trial for the Midlands Grand National.