Karthi's next film was the action–masala "Siruthai" (2011), a remake of the 2006 Telugu film "Vikramarkudu". He played two roles; a thief and a police officer. Karthi's performances received favourable reviews. Malathi Rangarajan of "The Hindu" wrote: "Karthi looks and performs better with every film. "Siruthai" exemplifies the observation". Pavithra Srinivasan of "Rediff" wrote: "But the film belongs to Rocket Raja (Karthi), the sort of adorable ruffian Tamil cinema has been missing for a while. He picks pockets, slices off handbags, charms women and even bashes (!) them up without a single jolt to his conscience." Despite gaining mixed critical response, the film achieved financial success, becoming one of the highest-grossing Tamil films of 2011. In 2011, "Siruthai" became Karthi's biggest commercial success, cementing his position in the Tamil film industry. "Sify" said that Karthi had become " ... one of the hottest stars in Kollywood". He made a special appearance in a song in K. V. Anand's "Ko" (2011), alongside other prominent actors from Tamil cinema.