In an entertaining, seesaw contest a vintage Steven Gerrard strike looked set to win the game for Brendan Rodgers' visitors after former City player Daniel Sturridge had controversially equalised Edin Dzeko's opener.
But, with 12 minutes remaining, Reina, whose Liverpool career remains in doubt beyond the end of the season, then foolishly rushed from his goal to be beaten by Sergio Aguero and the Argentine superbly finished from an almost impossible angle.
It could be viewed as a point gained for City but Roberto Mancini's team are now still nine points behind derby rivals Manchester United at the top of the table with 13 matches remaining in the season.
Liverpool had the better of the early possession and, shortly before the quarter-of-an-hour mark, Pablo Zabaleta had to prevent Sturridge from scoring the opener after the striker had rounded goalkeeper Joe Hart from a long ball.
However, Rodgers' team paid the price in the 23rd minute for failing to make their opportunities count, as City did well to work the ball down the left for Dzeko to finish James Milner's low cross.
Liverpool's misery, though, was short-lived as Sturridge hit a lethal 20-yard equaliser, which left City furious the game had not been stopped for a foul or that the ball had not been put out of play due to Dzeko lying up field with an injury after a challenge by Daniel Agger.
It was up to referee Anthony Taylor's judgement whether to stop the game but City, who conceded a goal for the first time in 2013, were still unimpressed, with Dzeko booked for his protests while Sturridge decided not to celebrate against the club where he started his career.
The equaliser rattled City and they finished the first half in the nervy form they had started the game, with stand-in captain Zabaleta and Hart involved in a dreadful mix-up which resulted in the full-back almost scoring an own goal.
Liverpool made a dominant start after the break and thought they had a penalty when Sturridge went down under pressure from Joleon Lescott but the £12million January signing was booked for diving.
Roberto Mancini did not like what he was seeing and replaced Matija Nastasic with Aleksandar Kolarov in order to switch to a three-man defence of Gael Clichy, Lescott and Zabaleta.
City improved after the tactical change but Liverpool, inspired by the excellent movement and running of Sturridge, continued to create the best chances and Suarez wasted another when curling wide with his right foot.
With City struggling to create much threat on Jose Reina's goal, it was a surprise Carlos Tevez remained on the bench among Mancini's substitutes, which did not include Mario Balotelli after his January transfer move to AC Milan.
And the home team paid the price with just more than a quarter-of-an-hour remaining when Gerrard rolled back the years with a stunning chest control and 25-yard volley which left Hart with no chance.
But, in the 78th minute, Reina rashly charged off his line to the left-hand side of the penalty area in an attempt to win the ball only to be beaten for pace by Aguero, who skilfully curled the ball inside the far post to ensure a share of the points.