Wenger concerned by Giroud's hamstring injury
Giroud's rare opportunity to start was ruined when he limped off clutching his right leg in the 78th minute.
Francis Coquelin was also hampered by cramp during Tuesday's quarter-final clash but is expected to be available for Friday's visit from Liverpool.
The news is less encouraging for France striker Giroud, who appears set to miss the festive period.
"It looks like that. We have to wait. Nowadays you do the scan 48 hours after the injury," Wenger told reporters at his post-match news conference.
"That will happen on Thursday, then we will have a precise kind of grade on what his hamstring [injury] is.
"When you listen to him, the pain is quite big, but the grade is not always linked with the intensity of the pain.
"In his statement [to me], it does not look very good."
Danny Welbeck netted a first-half winner with the game's only shot on target to move the Gunners into the competition's semi-finals for the first time since 2010-11.
11 – Danny Welbeck has ended a run of 11 games without a goal in the League Cup, netting his first in the competition since October 2009 (vs Barnsley). Overdue.
— OptaJoe (@OptaJoe) December 19, 2017