Fehily has been called up after Lynch suffered minor injuries when he was unseated from Mister First in the Topham Chase yesterday.
Lynch's agent Frosty Kelly said that he wouldn't be riding today but could return at Limerick tomorrow. "He won't be riding today as he's very sore," said Kelly.
"You have to be 100% to ride in the National, so he'll give it a miss.
"It's nothing too serious - he got a bang on a leg and the X-rays were all clear."
Lynch was more fortunate than Liam Treadwell, who also fell in the Topham Chase and suffered a cracked collarbone.