Both sides had chances to win it but in the end it was Mohamed Salah's header than somehow squirmed in through Toby Alderweireld and Huge Lloris and over the line at the Kop end.
Jurgen Klopp's side held on for the closing seconds to claim a huge three points to move back above Manchester City by two points having played a game more - the 24th lead change in an amazing race for the Premier League table.
After a bright start by Tottenham, Liverpool took total control of the game, with full-backs Trent Alexander-Arnold and Andy Robertson having acres of space out wide as the three at the back formation played by Spurs really struggled.
It was Robertson who grabbed his ninth assist of the season in tremendous fashion with a deliciously whipped in ball from the left that gave Firmino the easiest of headers from close range.
Chances came and went for the hosts with Sadio Mane firing a curler inches wide and Salah threatened on a couple of occasions but unable to find the target.
Read Sporting Life's analysis of the remaining fixtures in the Premier League title race...
Mauricio Pochettino was in the stands serving the second game of his ban, but his half time tactical switch and pep talk did the trick as Tottenahm emerged a different side and made it much more of a contest.
Harry Kane was behind the equaliser, as he fired a wonderful cross-field ball from a quick free kick to Kieran Trippier, whose cross was scuffed on by Christian Eriksen into the path of Moura who kept his composure nicely to beat Alisson.