|Ruby Walsh - Getty Images|
Ruby Walsh was ruled out of the Grand National with a fractured wrist after two falls at Aintree on Friday.
The two-time winner was set to ride the Willie Mullins-trained Sir Des Champs in Saturday's race
Walsh, 36, gave up his final two rides on Friday after first falling on the 1-5 favourite Vautour in the Melling Chase and then on Blood Cotil in the Topham Chase.
Nina Carberry will deputise for Walsh aboard Sir Des Champs.
Carberry joins Walsh's sister Katie, rider of Ballycasey, in the line-up for the 169th staging of the race, which has never been won by a female jockey.
Trainer Willie Mullins confirmed on Twitter than Carberry will replace Walsh in the Grand National, with Paul Townend getting the nod for Walsh's other rides on Yorkhill in the Mersey Novices' Hurdle and the favourite Douvan in the Maghull Novices' Chase
Mullins earlier played down the severity of Walsh's injuries after he did not take up his mounts on Bellshill in Sefton Novices' Hurdle or Battleford in the final race of the day.
"As far as I know he stood himself down and has decided to take rest of the day off. He'll be fine for tomorrow," Mullins said.
Sir Des Champs, the 2013 Cheltenham Gold Cup runner-up, was a 40-1 chance before the field was finalised on Thursday, but his odds halved after Walsh was confirmed as jockey.
Nina Carberry won the Fox Hunters' Chase at Aintree riding On the Fringe in 2015
Sir Des Champs will be the sixth ride in the Grand National for Carberry, who is the sister-in-law of Ruby Walsh.
She made her National debut on Forest Gunner in 2006, finishing ninth. Her best finish was seventh aboard Character Building six years ago.
Carberry was only cleared to ride in this year's National after the British Horseracing Authority overturned a ban in March because of "ambiguous wording" of a rule.
Her late call-up means two women will ride in Saturday's race as Ruby's sister Katie Walsh is on Ballycasey, also trained by Mullins.
Katie Walsh achieved the best Grand National finishing position by a female jockey when third aboard Seabass in 2012.
On Friday night, Sir Des Champs was rated about a 20-1 chance by bookmakers, while Ballycasey was 66-1.