Gray shrugged off a toe injury to play the full 90 minutes in Tuesday's crucial 2-1 home win over relegation rivals Watford at Home Park and came through unscathed.
Argyle made one change to the side that won 1-0 at Wolves with on-loan Blackburn winger Alan Judge recalled in place of Chris Clark and Judge could start once again.
In-form top scorer Paul Gallagher, also on loan from Blackburn, took his season's tally to 11 with both Plymouth goals against the Hornets and has now scored four goals in three matches.
Reading manager Steve Coppell has no fresh injury concerns.
Coppell saw his side finally end their goal drought in the 2-1 win at Sheffield Wednesday in midweek and will travel with the same squad.
Shane Long came off the bench to fire in a late winner at Hillsborough but is unlikely to force his way into the starting line-up as Coppell has consistently said this season that he sees Long as an impact player.
That should see Noel Hunt continue alongside Kevin Doyle, with Leroy Lita set to again miss out on a place in the matchday 16.
Jay Tabb made his first start against the Owls but lasted just 45 minutes before he was replaced by Jimmy Kebe and could be back on the bench while defender Ivar Ingimarsson is a long-term absentee and out for the rest of the season with a knee injury.
Club captain Graeme Murty is back from his loan spell with Charlton after another calf injury while David Mooney has joined Norwich on loan.
Sporting Life