The Lancashire club earned many plaudits for the way they performed in the 1-1 draw with City at Ewood Park as Scott Dann's second half strike cancelled out Alvaro Negredo's opener.
However Robinson, who made his first in 13 months in the Ewood match, knows that at the Etihad, City are strong favourites.
"You see the way they play at home and the number of goals they've scored, we'll be going into the game as massive underdogs," said the goalkeeper.
"But as last week, we've got absolutely nothing to lose, nobody has given a chance, we've got to go there and show people what we can do.
"Yes it is a test, they've scored six, seven past teams at home this year, but we've got a stage where we can show our talents and show what a good team we are."
Tickets will go off sale at Ewood Park at 4.00pm today. Supporters can buy on the night at the ground from the stadium ticket office at the north end of the Etihad. Prices are from £15 Adults, £10 Seniors/16-21yr-olds and £5 Juniors.
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