Campbell then lit up the home fans when heading home Peter Whittingham's inswinging corner in the 79th minute before sending them into raptures with another header, this time form Don Cowie's corner from the left.
Alvaro Negredo gave City some hope with his first goal for the club in injury time with a header from David Silva's net cross but it wasn't enough as the Bluebirds completed a stunning comeback to take all three points.
On Saturday, Arsenal returned to form with a 3-1 win at Fulham thanks to a double from Lukas Podolski who rifled home in the 41st minute and then angled another effort into the bottom corner in the 68th after Olivier Giroud had got on the end of a mishit Aaron Ramsey effort to prod home past David Stockdale in the 14th minute. Darren Bent, on loan from Aston Villa, got one back for the Cottagers with just over ten minutes remaining.
Liverpool continued their bright beginning to the campaign with a 1-0 triumph at Aston Villa thanks to Daniel Sturridge's second goal in a row whilst ten-man Hull City opened their account with a 1-0 home win over Norwich City courtesy of Robbie Brady's 22nd minute penalty.
Southampton scored a late goal to rescue a 1-1 draw at home against Sunderland, Stoke City came from behind to defeat Crystal Palace 2-1 at home, Roberto Soldado netted a second penalty of the season as Tottenham beat Swansea City 1-0 as West Bromwich Albion and West Ham United forced 0-0 draws at Everton and Newcastle United respectively.
2013/14 Barclays Premier League scores