Bellerin was substituted at half-time in Sunday's 2-2 draw with Crystal Palace, the 23-year-old replaced by Stephan Lichtsteiner.
The full-back is one of five Gunners defenders currently sidelined with injury, leaving coach Unai Emery with very few options ahead of two games in quick succession.
Bellerin suffered a right thigh injury at Selhurst Park and Arsenal have confirmed he will be assessed ahead of Liverpool's trip to Emirates Stadium on Saturday – where a win would move Arsenal to within one point of Jurgen Klopp's side.
The defender has been an important part of Arsenal's squad this season, delivering four assists in 10 Premier League contests.
Bellerin had confirmed his injury on Sunday through social media, though he did not detail how long he would be out, saying he was working to come back quickly.
Already trying my best to come back asap pic.twitter.com/z808NfirE3— Héctor Bellerín (@HectorBellerin) October 28, 2018
The Gunners will also be without Konstantinos Mavropanos and Laurent Koscielny, as the wait for the duo goes on.
Mavropanos is expected to return to training next month after a groin problem, while Koscielny's recovery from Achilles surgery has seen him start to be reintegrated back into the squad.
Arsenal will also be without Mohamed Elneny for the next two weeks due to a thigh problem.
However, the Gunners could receive a fitness boost in the form of Nacho Monreal and Sead Kolasinac.
Both players are nursing hamstring injuries, but will be checked prior to the cup match and may be in line for a return against the midtable League One side.