The Blues twice came from behind in what was a pulsating contest at the Etihad with the scores level at 2-2 after 90 minutes.
That then led to the drama of a penalty shootout and when Mateo Kovačić saw City’s third effort saved the advantage was suddenly with the Seagulls.
However Rulli, making only his second appearance for the Club, produced stunning back-to-back saves from first Yasin Ayari and then crucially Lewis Dunk to seal a 4-3 victory on penalties.
City’s reward is a quarter final tie at home to Bradford – and for the boss it was no less than Ruilli deserved – though he stressed Gianluigi Donnarumma would assume goalkeeping duties in Saturday’s league clash with Brighton.
“Apart from the penalties, overall he was good,” Maresca reflected.
“It was not easy because they go man-to-man, aggressive.
“First half we went long to Floyd and second half on the floor. He made one good save too. He was good.
“He’s working well but he knows exactly his role. Absolutely no doubt. Saturday is Gigio plus 10.”
Maresca also revealed that the Blues had so far in his reign never specifically concentred on penalties ahead of tonight’s satisfying outcome.
“Since I am here, we’ve never practised it,” Maresca said.
“They are all good, but it always happens that the one that scored during the game (Kovačić) missed the penalty.
“I was happy with the way we planned the game, the rotation and very happy with the ones playing inside the pitch.”
