He said: "It is very frustrating. We knew these three points would have been very important for our season and though we have one point we have not reduced the gap by very much."
"We knew Sunday's game was going to be important. Now it is even more important," he added.
But Rafa remained buoyant, and believes his team are capable of overcoming their rivals on Sunday.
He said: "I am always confident. We can only try our best and we will keep working hard to get fourth place. But we know we must play better than this or have a bit of luck if we are going to win games. We know Everton might come here and play the same way as Blackburn and we must play better on Sunday. We know how important the derby is now. We have to win."