The 26-year-old Irishman played the full game for the reserves in the 5-2 win at Gateshead.
It was his third appearance for the second string since his return from a knee injury which he suffered on the opening day of the campaign.
Flood dislocated his kneecap during the 3-1 home defeat by Ipswich on August 7 and has been battling his way back since.
The Teessiders entertain Barnsley at the Riverside Stadium on Saturday having put together a six-game unbeaten run which has lifted them 12 points clear of the npower Championship drop zone with the teams below them having only five games left to play.
Flood could be included in the squad as manager Tony Mowbray attempts to cover the loss of Marvin Emnes, who serves the second leg of a three-match ban.
Source: PA
Source: PA