The second half started slowly but Liverpool found urgency late on and were rewarded with breakaway goals from Mohamed Salah and Henderson to seal a fantastic away win and keep the pressure on Man City who play in the FA Cup this weekend.
And fans gleefully welcomed back their hero at a crucial time for the club's season.
Liverpool were forced to come from behind to beat Southampton 3-1 and return to the top of the Premier League table this evening.
The speed at which Salah has amassed Premier League goals for Liverpool leaves him in good company among the top-flight's greatest strikers.More news: Joe Biden addresses allegations of inappropriate touching in new video
Some good defending on a pair of Southampton corners led to a blistering counter-attack for Liverpool as Salah picked up the ball in his own end, ran the length of the field and finished from 18 yards away to send the travelling supporters into ecstasy at St Mary's.
Keita looked like he was about to burst into tears, his first Liverpool goal was a moment to treasure for the ex-Leipzig player. That's the most important thing for us.
Substitute Jordan Henderson made a huge impact on the game and his determination was rewarded in the final five minutes as he capped off the win with Liverpool's third.
Roberto Firmino had appeared as an option on Salah's left on the play, but when asked if he ever pondered squaring the ball to his Brazilian teammate, Salah replied: "Not at all!"
The Reds went a goal down in the opening ten minutes after Shane Long put the visitors ahead with a simple finish. "But I've had conversations with the manager and I felt as if I could affect it a little bit higher up".
"To make a difference and have an impact, that's what me and Milly wanted to do and thankfully we've done that and managed to win the game". I am really proud. Tidy in possession and thankfully was not called on for much work in the second half.