Second row forward Szostak has played over 100 games for the club but the likes of Joe Hirst, Michael Knowles and Peter Green all played superbly in the back row during the win against York City Knights.
McDonald, who has also been suffering with a rib injury, can play at either stand-off or loose-forward. This versatility will probably mean a berth on the substitutes bench for Friday’s game.
“It’s the kind of problem you want to have,” said Aston on the Sheffield Star website. “It gives us competition for places which is important.”
The Dewsbury game is the first of two consecutive home games in which the Eagles will be looking to gain maximum points to stay in touch with Championship leaders Halifax.