Fox, who took over as stable jockey at trainer Lucinda Russell’s Kinross yard following the retirement of Peter Buchanan, has been in the saddle for One For Arthur’s two wins this season, with the pair most recently impressing in the Classic Chase at Warwick in January.
The young rider has been sidelined by injury since suffering a fall at Carlisle on 9 March.
Russell said: “He’ll ride at Carlisle on Wednesday. I’m not sure how many rides he’ll have [at Carlisle], I’ll see what the entries are like, but he’ll definitely ride in the bumper.”
Fox is set to have a warm-up ride over Aintree’s famous fences aboard Imjoeking in Friday’s Topham Chase.
“As long as Imjoeking gets in the Topham, Derek will ride him, so hopefully he’ll get a spin over the fences before the National,” Russell added.
“It’s just fantastic to have him back. He has such enthusiasm and so many ideas. He’s a big part of the yard.”
Ahead of One For Arthur’s big-race assignment, Russell added: “He seems very well in himself. We’re just ticking off the days at this stage and trying not to think about it too much.
“We need to try to think of it as just another race.”
Two horses who will miss the big race are Carlingford Lough and Ziga Boy.
The John Kiely-trained Carlingford Lough, who was last seen finishing fourth when bidding for a third successive victory in the Irish Gold Cup at Leopardstown in February, was due to carry top-weight of 11st 10lb.
Frank Berry, racing manager to owner JP McManus, said: “He’s not going to run on Saturday. He’s going to wait for the Irish National or the Punchestown Gold Cup. He could run in the Irish National.”
Ziga Boy was a general 50-1 shot having won the last two renewals of the Sky Bet Chase at Doncaster, but he is set for a lengthy spell on the sidelines after suffering a tendon injury.
Dan Downie, racing manager for the Axom syndicate that owns the Alan King-trained grey, said: “It’s very disappointing, obviously. We nearly got there, but we all know how hard it is to get these horses ready for a big day and unfortunately it wasn’t meant to be.”
l Quixote has yet to really put his best foot forward in Britain, but all that can change with victory in the sunbets.co.uk Handicap at Southwell.
The German-bred seven-year-old has plied his trade in Europe in previous years, winning a Listed event in Germany back in 2013 and lifting a handful of very moderate contests on the all-weather in France, too. He will be having his first start for David Loughnane here, having initially been campaigned by Tony Carroll in this country with a mixed record of success.
Quixote did not really show too much on the turf last summer or in the pre-Christmas all-weather period, but his fourth at Lingfield in January marked him as the type to be finally finding his feet.
Lining up in a similar event to this, he had an unfavourably wide draw but soon got to the front and only narrowly failed to make all, eventually settling for a one-length fourth after being swamped in the finish.
The handicapper has steadily eased him down the ratings from a starting point of 97 to his current perch some 7lb lower and that ease can prove crucial.