Leeds United boss Daniel Farke confirms two absentees for Championship home game with Middlesbrough FC
Gelhardt is ruled out with a slight hip issue, but it will not keep him out for an extended period, Farke confirmed.
The former Wigan Athletic player has endured a frustrating camapign thus far and has not featured since the win at Millwall in September.
He fractured his hand in training at the start of November and has now been hit by a fresh problem.
Meanwhile, Firpo, who only returned to action earlier this month after suffering a knee injury on the eve of the new season, is sidelined for most of this month with a hamstring issue.
The left-back has made just three appearances this term.
On his side’s team news ahead of the Boro encounter, Farke said: "It's similar, but not equal. Two players are not available for this game.
"One is ‘Joffy’ Gelhardt, who has a little hip problem, so he is not in contention for the game. Junior Firpo reported some problems with his hamstring after the last game.
We have scanned him and he has a strain and he will be out for about three weeks."It is not a major problem (with Gelhardt). He will just miss this game and it is just a light problem, although he is not in the mix for tomorrow.”
Boro are sweating on the fitness of key duo Hayden Hackney and Dael Fry ahead of the Elland Road appointment.
England under-21 midfielder Hackney, widely regarded as one of the best young schemers in the second-tier and the reigning Championship young player of the season, has missed the club's last two games against Bristol City and Preston North End with a groin injury.
Fry sat out the midweek victory over Preston with a knee issue.
The absence once again of Fry will leave Boro light in their central defensive options, although Matt Clarke came off the bench to make his first appearance in just over a year following a serious back injury.
Darragh Lenihan and Tommy Smith are out with long-term injuries and will miss the rest of the campaign.
Left-back Lukas Engel is among Boro's other injury concerns, having missed the midweek win with a knee problem.
Definitely out alongside Lenihan and Smith are Lewis O'Brien, Riley McGree and Marcus Forss, while Smallwood is ineligible against his parent club.