Well somehow am not surprised because this is exactly what team that have nothing to play for that are in the relegation zone do, because they tend to spoil things for the clubs that are in desperate need and Manchester city know how important this game is to them but somehow they failed to score and Southampton were even close too to score on one or two occasions. The funny thing is that third place is what they need to be sure of champions league football owing to the fact that one slot as you stated will be taken by the winner of the Europa league.
It was unexpected that Manchester City would fail to win against a team like Southampton. We have seen better performances from Manchester City in the last few matches. City have won four consecutive matches before this. Since the opponent in this match was Southampton, who are at the bottom of the points table, we all expected City to win. Many gamblers lost their money today.
Manchester City could not score a single goal today. I would say this is their failure. Southampton's defense was not strong. Even then, City could not score any goals. Along with 72% ball possession, a total of 26 shots were taken by City players. Despite a lot of attacks, the team failed to score a goal.