An own goal deep in stoppage-time from Neil Taylor rescued a point for Chelsea in the 1-1 draw at Swansea on Tuesday night.
That result coupled with a 3-1 win for Tottenham over Wigan means the Blues are now seven points behind their London rivals in the battle for third.
They are also 12 points behind joint leaders Manchester City and Manchester United.
On his official website, Cech said: "We don't even have to mention the word 'title' because the Manchester clubs will not drop many points.
"That's the reality.
"I still think it is realistic to target the third sport, though. For that we will need to succeed in Sunday's tough match (against Manchester United)."
Chelsea finished the game at the Liberty Stadium with 10 men after Ashley Cole was dismissed late on, ruling him out of Sunday's game.
Cech felt that a draw was a fair result as Swansea had the better of the first half and Chelsea the second.
He added: "In the first half, we were not playing well at all but after the break it was completely different.
"We put Swansea under pressure, did not allow them to pass the ball at ease. However, once again we were unable to give the final pass into their box.
"Even with 10 men we were pushing ourselves forward and the effort was rewarded with an equaliser in stoppage time.
"Bosingwa's shot was deflected by a Swansea player, so in the end we must take the point.
"Naturally, we wanted to win but nobody has it easy playing at Swansea. They have lost just one home match this season."
