Glenavon boss Gary Hamilton was hoping to avoid a potential goalkeeper crisis last night.
McGrath (25) has joined to the end of the season and will make his debut against former club Ballinamallard United on Saturday.
Glenavon hadbeen facing up to Saturday’s trip to the Mallards with no recognised number one available.
Andy Coleman serves a suspension following his sending off against Glentoran in midweek, while John Connolly has been ruled out for the rest of the season after breaking his tibia in reserve team action.
But at the eleventh hour Hamilton has drafted in McGrath.
“We are delighted to get James signed up and available for us,” Hamilton said.
“It is a position we needed filled as it has been a nightmare week for us, with John’s injury and then Andy’s sending off.
“James will come in for Saturday, but he knows he will have to fight for his place for the rest of the season.
“We are just pleased we have got some cover in as we were looking at Brian McCaul or someone having to go between the posts which would have been far from ideal.”
Hamilton is hoping Glenavon can boost their top-six prospects with victory over Ballinamallard tomorrow.
The Lurgan Blues are eight points adrift of Ballymena United, but boast two games in hand.
“We have had a tough run of games, but hopefully we can start picking up points again,” Hamilton added.