The Reds started the game showing clear signs of fatigue with their passing not as crisp as it can be.
They went behind in the opening 10 minutes as Ryan Bertrand's cross and Pierre-Emile Hojberg's header to Shane Long was converted by the Irishman to put the hosts ahead.
Liverpool were still off the pace but prodded at the Saints' defence as the half wore on and were finally level in the 36th minute as Keita headed past goalkeeper Angus Gunn.
The Reds finished the first half strongly but will need to get at least another goal to earn a valuable three points in the title race.
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