The former City Ground defender limped off during QPR's win over Middlesbrough and Steve McClaren is unsure whether he will be fit in time.
The former Reds centre-back, who turned out for the City Ground outfit between 2008 and 2012 (Transfermarkt), limped out of QPR's 2-1 win over Middlesbrough last Saturday.
Lynch's departure just after the break temporarily left Steve McClaren's side down to 10 men and Boro drew level during this time via George Saville.
However, QPR made sure that Pawel Wszolek's early opener was not in vain as Nahki Wells slotted home on the hour for a three-point haul at Loftus Road.
McClaren, another former Forest employee, isn't too pessimistic about the chances of Lynch joining him for a return to Nottingham, though it remains to be seen whether he does recover in time.
"It’s just a dead leg. It stiffened up over half-time,” the QPR boss told Football London. "We’ll have to wheel him out next week because it’s a dead leg and hopefully not too bad."
Forest will be hoping to kick on from Monday night's 0-0 draw with Derby County at Pride Park in a bid to claim all three points in their last game before Christmas.
QPR's history at the City Ground isn't the best, the west Londoners not having won there in their 34 previous trips (11v11).