The Roma boss, who had questioned the Ireland striker's impact in Serie A only 24 hours earlier, praised the 21-year-old for a display he described as "beautiful" and full of "spirit".
Ferguson struck twice in the first half in Glasgow, guiding Roma to a comfortable victory against the Scottish champions in the second match of the five-game group stage. His second finish, a precise right-footed effort after a clever move, drew particular admiration from Gasperini, who had been reported in Italy earlier in the week to be considering ending the youngster's loan spell and sending him back to Brighton in January.
Instead, Gasperini has now urged patience.
"It's never easy to win away, especially on these beautiful and historic pitches," Gasperini told Sky Sports Italia. "Pisilli, Ferguson and the other changes performed well. They give us options to expand the squad in a period when we need to make important assessments."
He added: "Celtic came into the match on the back of a series of victories. Playing in Europe is different to playing in Italy, and you often face very strong strikers. It's a different type of football."
Turning to Ferguson's performance, Gasperini said: "During the game he did what he often does in training. Beyond the goals, his overall performance matters. He played with spirit and intensity. He is still young and we have to be patient. His second goal was beautiful, and he showed real quality."
The remarks contrasted sharply with his pre-match comments, when he had said: "I have nothing against Ferguson personally. It is about performances. He has had a lot of chances. We want to wait for him to develop, but he has to do better — not just technically, but in terms of attitude."
Ferguson, who has endured a demanding start to life in Serie A, welcomed the faith.
"Even though it has been a difficult start to the season, I have always trained, worked hard and tried to give my best. Tonight it went well," the Irishman said. "I actually like playing in this type of stadium. I'm Irish, so it feels almost like home.
"Gasperini? Every day he tries to push me and the whole squad to the maximum. He expects a lot from me and demands intensity, and that is why we work well together."
Sebastian Hoeness said his VfB Stuttgart side "did exactly what they came to do" after a commanding 4-1 win over Maccabi Tel Aviv kept their Europa League push firmly on track.
Jose Mourinho has said Benfica "deserved everything" after they overpowered Napoli in Lisbon to keep their Champions League play-off hopes alive with a vital 2-0 victory.
Liverpool head to the San Siro tonight looking to achieve a feat only Bayern Munich have managed in the Champions League era, winning three away matches against Inter Milan in the competition.
Chelsea have received double fitness boosts ahead of their Champions League trip to Atalanta, with Enzo Maresca confirming positive news on both Cole Palmer and Liam Delap.
