(CNN) -- Manchester City shrugged off a penalty miss, an injury to striker Sergio Aguero and falling 2-1 behind in the second half, to register a thrilling 3-2 opening win over Southampton Sunday in their defense of the English Premier League title.
Samir Nasri scored the clinching goal with 10 minutes left at the Etihad Stadium to end the bold challenge of the newly promoted visitors, who had threatened a victory of their own.
"We deserved to win the game. They didn't have any chances in the first half and we had four or five incredible chances," City manager Roberto Mancini told AFP.
"We made some mistakes but the big problem was we missed chances when it was 1-0 and then it changed.
"The first two or three games could be like this because we are not 100 percent."
Argentina star Aguero scored the crucial injury time winner against Queens Park Rangers in the final game of last season as City edged out arch-rivals Manchester United, but he lasted just 11 minutes before being stretchered off.
He was caught awkwardly by a challenge from Nathaniel Clyne and twisted his knee to be replaced by Edin Dzeko.
In the 18th minute, City won a penalty as Carlos Tevez was pulled down by Jos Hooiveld, but Spain World Cup star David Silva saw his weak effort saved by Kelvin Davis.
It was left to Tevez to make the breakthrough just before the break as beat the offside trap to fire past Davis.
Any idea City would ease to victory were quickly dispelled in the second half as Southampton substitutes Rickie Lambert and Steven Davis were on target in quick succession to put their side 2-1 ahead.
But Dzeko leveled it at 2-2 after being set up by Yaya Toure and Nasri clinched three points for the champions after latching on to a loose ball in the penalty area.
Earlier, Belgium's Eden Hazard made a fine debut for Chelsea as the Champions League winners beat Wigan 2-0 at the DW Stadium.
Hazard, a big money signing by Chelsea from Lille in the close season, set Branislav Ivanovic on his way to score an early opener.
Only two minutes were on the clock and Wigan, who narrowly avoided the drop last season, were soon 2-0 down after Hazard was pulled down for a penalty.
Frank Lampard slotted home the spot kick and Robert Di Matteo's men were already on their way to a winning start.
Victor Moses, a reported target for Chelsea, troubled the visitors as they defended their lead, but they held on for the three points.