World Supersport rider Luca Scassa will stand in for the injured Karel Abraham in the Cardion AB MotoGP team at Aragon.
The Italian raced in the World Superbike Championship from 2008-10 after winning the former year's Italian Superbike title.
Scassa stepped back to Supersport in 2011 and finished fifth, and returned to the series with the Intermoto Kawasaki team this year after a disappointing season in British Superbikes.
Abraham will have to miss the rest of the season following surgery on shoulder injuries he sustained at Indianapolis in August.
His father Karel Abraham Sr, head of the Cardion team, said Scassa would be assessed in the Aragon Grand Prix before a longer-term decision was made.
"Luca has ridden more then 50 races in WSBK and he has enough experiences to run on the MotoGP bike and to jump to the championship," said Abraham.
"It was important for us to find a rider who can manage so specific a machine as the Motogp bike and who knows the circuits where the next five races will take place.
"The first race waiting for us is next weekend in Aragon, where Luca achieved this year's best result in WSS."
Cardion was informed by Dorna that it had to take a rider with MotoGP or WSBK experience for the seat, precluding any hope of bringing in another Czech rider as Abraham's substitute.