The 41-year-old 'Bang Bang' actor took to Twitter and lauded the singer, who opened the second episode of the show with his number.
"Rockstar. Serious talent. Such freedom. Mazaa aa gaya!," the actor tweeted, along with the link of the song.
Singer Adnan Sami also praised Zafar, 35, for the song. "Fabulous performance of 'Rockstar'!!! Incredible highs!! Enjoyed it immensely!!"
'Kai Po Che' director Abhishek Kapoor tweeted, "This guy can hit some serious notes. Unmissable @AliZafarsays #rockon bro."
Ali Zafar, who made his debut in 2010 with 'Tere Bin Laden', was last seen in Ranveer Singh-starrer 'Kill Dil'.