Spurs' chances were not helped by the early second-half dismissal of Danny Rose, and Sigurdsson said that once they were reduced to 10 men there was only likely to be one winner.
"Playing against them with 11 men is tough but with 10 men is even tougher against quality players like this, because they are so good going forward and it's hard to defend against them," he told the club's official website.
"I think City started the game better and they could have scored a few goals in the first 25 minutes or so.
"Then we got back into the game and we started not too badly in the second half. Obviously the penalty and the sending off made it quite difficult in the second half."
The result leaves Spurs fifth in the Premier League table.