Jurgen Klopp opted to hand the one-time England international the captain’s armband in the absence of rested skipper Jordan Henderson.
The 23-year-old has enjoyed a special week in his blossoming Liverpool career after he signed a new three-year deal with the Merseyside outfit on Friday evening.
Flanagan missed 619 days due to a serious knee injury before he returned to the Liverpool side for their 3-0 win against Exeter City in the FA Cup in January.
Philippe Coutinho broke the deadlock with a long-range strike before Daniel Sturridge doubled the away side’s advantage.
However, Sothampton fought back in the second half as Sadio Mane and Graziano Pelle levelled the game at 2-2 with seven minutes to play before the Senegal star netted a late winner.
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