The Argentine said his side were unfortunate not to get the goal they were looking for at the Vicente Calderon but admits Jose Mourinho's men are now favourites to progress
The Liga leaders were the far more enterprising of the two sides but struggled to penetrate a resilient Chelsea back four, despite the constant stream of crosses.
Diego Costa saw a volleyed effort charged down in the first half, while Gabi's free-kick from distance was well held by substitute Mark Schwarzer, who replaced Petr Cech in the first half after he suffered a dislocated shoulder.
Chelsea defender John Terry also came off in the second period with an ankle injury, but Simeone feels the visitors will be the happier of the two sides after a 0-0 draw in the Spanish capital.
"It was a tough game where nobody could get an advantage," said the Argentine.
"We could not find the goal that would have won the match. It was an intense game with both sides fighting to get to the final.
"They have the advantage with this draw, but whoever wins the next game will go to the final."