The Frenchman, who has been out of action since being substituted during his side's 2-1 defeat to Chelsea on September 29, provided an assist for Andre Santos to open the scoring against West Brom's youngsters.
Arsenal midfielder Abou Diaby stepped up his return from injury by playing 65 minutes for the club's under-21 side on Wednesday.
And, after getting through over an hour unscathed, the midfielder was withdrawn to be replaced by Conor Henderson.
Diaby has made just six first-team appearances so far this season due to his struggles with injury.
Back in November, Arsenal manager Arsene Wenger admitted the 26-year-old's absences were a 'concern', but stopped short of writing him off completely.