City's dip in form continued as Guardiola's team fought for a 1-1 draw against Southampton at the Etihad
The stalemate was a fifth consecutive game without a victory for City, as Kelechi Iheanacho's eighth goal in his last 11 league games cancelled out Nathan Redmond's first-half opener for Southampton, which owed much to an extraordinary mistake by City defender John Stones.
City, after winning their first 10 games under Spanish coach Guardiola, have suffered a major dip in form.
"We have to analyse what is the situation," Guardiola told the BBC.
"In the period, apart from at White Hart Lane against Tottenham (losing 2-0) it's been good. Against Everton and Barcelona -- when it was 11 v 11 -- the displays were as good as those in the first 10 games."
Guardiola, who saw his expensively assembled side held 1-1 home to Everton last weekend, had spoken passionately in the wake of the midweek 4-0 defeat at former club Barcelona about his desire to stick to his footballing philosophy.
Those beliefs, however, must have been sorely tested in a first half in which his side failed to test Fraser Forster in the Southampton goal and fell behind to the visitors.
The Saints went ahead in the 27th minute following a disastrous back pass from England centre-half Stones, who nonchalantly laid the ball back into the City penalty area despite the presence of Redmond.
The forward retained his composure, beating returning skipper Vincent Kompany to the ball and rounding Claudio Bravo before converting into the open net.
"From watching them in preparation we knew they would give us chances, they only play three at the back," Redmond told Sky Sports. "I was anticipating it and it was just about keeping a cool head and putting the chance away."
The draw was enough to put City back top of the Premier League on goal difference from Arsenal, with Liverpool third. All three are on 20 points.
But following Bravo's costly defensive slip in the midweek Champions League defeat, it was another blow to Guardiola's determination to play attractive, passing football at all costs and a handful of home supporters booed the team off at the interval.
For all their defensive problems, however, City were equally ineffective at the other end in the first half --- their best effort coming when Stones had a 31st-minute effort ruled out for offside.
The defender appeared to have made amends for his earlier error when he headed home Kevin De Bruyne's free-kick only for referee Mark Clattenburg to rule it out -- a decision which replays suggested was harsh.
An early David Silva cross was easily picked out by Forster, Ilkay Gundogan shot just wide from the edge of the area and Raheem Sterling drilled a shot way off target.
Indeed, the Saints looked more likely to score, particularly on the break, with Dusan Tadic testing Bravo with an early cross-shot.
Guardiola wasted no time in altering his tactics at the interval, with Iheanacho replacing De Bruyne, who was clearly still below peak form following a recent injury lay-off.
City finally started to assert some control with Sterling's low 54th-minute cross just bouncing beyond Silva?s far-post lunge.
Moments later, Iheanacho equalised after a flowing move exposed gaps in Southampton's defence with passes from Fernandinho and Leroy Sane allowing the young Nigerian to sweep in a confident finish from six yards.
"They did it for themselves in the second half," said Guardiola of his players. "They changed the game, I didn't change the game. We did think we were going to win it, but Southampton didn't make it easy. They have good defenders and are good at everything."
City's passing, so inconsistent in the first half, also improved markedly after the break and a concerted attack ended with Sterling finding Iheanacho, who turned and centred for Silva, only for a deflection off a defender to save the Saints.
Sergio Aguero also twice came close for City, first with a stooping, off-target header and then with a determined run and low shot which flashed across the face of goal.