The result has allowed Sampdoria to jump clear into fourth-place.
Rossi said: "I have to get the best out of these strikers in the final weeks of the campaign, so that means taking into account bookings and tiredness. I knew Miccoli would be very useful in the final half-hour.
"We expected Cagliari to play the game of their lives, especially with a change of management.
"My team stayed professional and believed right to the end. If a side has spirit, it does not succumb easily."