Cech admitted Chelsea failed to kill off the game when they had the chance.
"We could have put the game beyond their reach but we didn't do and that's why they came back into the game," he said. "For their comeback they deserved a point.
"We had chances to kill the game off but we didn't do it.
"We kept organised and did what we had to do. For them it was a fantastic game and they had nothing to lose.
"When you get the opponent into this sort of mood it's difficult.
"We could have done it the easiest way possible and play four games and be qualified so now we have to do it the hard way."