Former quarterback Synjyn Days, a senior who switched positions before the start of summer camp, is likely to start in Laskey's spot, but he faces a tough task.
The Yellow Jackets (5-2, 2-2 Atlantic Coast Conference) take a two-game losing streak to Pittsburgh on Saturday and need to get a big push inside the Panthers' four-man front.
Pitt (4-3, 2-1 ACC) ranks fourth nationally in total defense, 18th against the run. Georgia Tech has the nation's No. 4 rushing attack, and Laskey, a senior averaging five yards a carry in 120 attempts, is a big part of equation.
Coach Paul Johnson said on Tuesday that team doctors don't know how long Laskey will be out.
Days is competing in practice this week against C.J. Leggett, a freshman whom the Jackets had likely planned to red-shirt.
''Truthfully, Synjyn is probably a more physical runner than Zach,'' Johnson said. ''Zach's got more experience and is a little more shifty, I would think.''
Former walk-on Matt Connors is another possibility, but Johnson and his staff are giving Leggett, a former standout at nearby North Gwinnett High School, plenty of chances in practice this week.
Johnson describes Leggett, who hasn't played this year, as the most explosive runner among the potential replacements.
''He may be the guy who can get a crease and go the distance,'' Johnson said. ''He's got great quickness and speed.''
In 16 carries this year, Days has averaged 5.6 yards. He scored a touchdown in the season-opening win over Wofford.
Laskey, the ACC's fifth-leading rusher, was injured in last week's 48-43 loss at North Carolina. He left the game briefly but returned for the final offensive possession.
In a 28-17 home win over Miami earlier this month, Laskey was at his best, lumbering through the line of scrimmage all night to tie a career-high with 133 yards on a career-high 29 carries.
Johnson insists that he feels comfortable with Days, Leggett or Connors filling in for Laskey at B-back in the Jackets' spread option formations.
Even without Laskey, the Jackets still have the ACC's fourth-leading rusher in Thomas, who's become adept at running the triple-option and attacking both the inside of a defense and its perimeter.
''I think we will be fine at that position,'' Johnson said. ''I'm not too concerned about it really. Zach's been a good player for us, but I think we've got guys who can play there.''
In snapping a three-game losing streak last week with a home win over Virginia Tech, Pitt held the Hokies to 26 yards rushing on 22 attempts.
The Panthers have an active secondary. Cornerback Reggie Mitchell had 10 tackles and two forced fumbles against Virginia Tech. Safeties Ray Vinopal and Terrish Webb each had two of Pitt's eight interceptions and are two of the team's top four tacklers.
Notes: In announcing Notre Dame's rotating schedule in the ACC over the next 10 years, the league has scheduled Georgia Tech to visit the Fighting Irish next Sept. 19 and host Notre Dame on Oct. 19, 2019. The Jackets and Irish will play again in 2021 at South Bend, Indiana, and in 2024 at Bobby Dodd Stadium.