Connections have confirmed Native River will miss both the Magners Cheltenham Gold Cup and Randox Health Grand National due to injury.
The 10-year-old was set to head to Prestbury Park in fine form, having won the Betfair Denman Chase at Newbury on February 8.
Native River beat Secret Investor, Might Bite, A Toi Phil, Valdez and Activial on that occasion and was available at around 10/1 for the Gold Cup at next month's Cheltenham Festival.
Colin Tizzard's charge also won at Aintree in December but assistant trainer Joe has revealed he will be forced to sit out the season with a tendon injury.
He told the Racing Post: “Unfortunately we have had to scratch Native River from the Gold Cup this morning. It's really disappointing but he's just had a little tear in the suspensory tendon at the back of his knee which is going to put him out for the rest of the season.
“He was a bit sore yesterday and again this morning, so we went in and scanned i, and just one of those injuries that happen. It's very disappointing, but that's horses.
“He'll be back next season for sure. It's not something we've thought about yet as we haven't known long, we told the owners and it's all pretty fresh.
“We need to focus on getting him right. It's not a major injury and on a normal basis he'll be fine by Christmas next year.”
Nicky Henderson's Santini remains the favourite for the Gold Cup, with last year's winner Al Boum Photo also well fancied.
Tiger Roll remains the 5/1 favourite for the Grand National, with Gordon Elliott's charge looking to become the first horse to ever win three in a row at Aintree.
