Diaby, 26, has not played for the club since suffering a thigh injury in a 2-1 defeat to Chelsea in September but played 65 minutes for the youth and reserve side on Wednesday.
He created an assist for Andre Santos before being substituted on 65 minutes for Connor Henderson.
Diaby was restricted to only four substitute appearances in the Premier League last season but had started the 2012-13 season in encouraging fashion.
The France international put in a man-of-the-match performance in a 2-0 win at Liverpool in September then scored for his country in a World Cup qualifier away in Finland.
However, the injury suffered at the end of that month saw him return to the sidelines.