The 21-year-old has not yet fully recovered from injury but was on the training pitch at Melwood.
It appears as though the Reds full-back did not take part in practice but was at least present on the pitch, giving photographers the thumbs up as he looks to make his return from injury.
Brendan Rodgers' side have suffered in defence so far this term and 21-year-old Flanagan will offer a timely boost whenever he does make his comeback to fitness.
Meanwhile, Liverpool's formation during the Arsenal game may have been revealed in the below picture from Melwood today. Indeed, Kolo Toure, Mamadou Sakho and Martin Skrtel were all photographed together alongside Brad Jones as boss Rodgers appeared to talk tactics with the quartet.
That suggests - although he was in training, as well - that Simon Mignolet may again be dropped from Liverpool's starting line-up, with the Reds once again deploying three at the back against Arsenal, as they did at Bournemouth.
The Gunners travel to Anfield on Sunday for a 4pm kick-off British Time. Rodgers, Liverpool's players and fans alike will all hope for a similar outcome to the 5-1 win against Arsenal last season. Here are the best pictures from training!