Megastar Amitabh Bachchan, who caught up with actors Ranbir Kapoor and Katrina Kaif on the sets of reality show "Bigg Boss 3" recently, is all praises for the latter and says she is a "modern day marvel".

"Katrina is a modern day marvel. From a non-Hindi speaking young shy and uncertain lady of 'Boom', she has grown and grown to become one of the most desired actresses in our fraternity, " Amitabh posted on his blog bigb.bigadda.com.

While Amitabh hosts the reality show, Ranbir and Katrina had appeared to promote their film "Ajab Prem Ki Ghazab Kahani", which released Friday.

"They (Ranbir and Katrina) were charming and involved and sweet. Ranbir as you all know is related to me. His cousin - Rishi Kapoor's elder sister's son is married to Shweta, my daughter.

"I wished them happiness and success, " he said.

In the meanwhile, Amitabh is himself busy charting the marketing plans of his forthcoming movie "Paa", being touted as his best work so far. He plays a 13-year-old suffering from progeria, a rare disease which causes premature ageing.