Why are Team India cricketers wearing black armbands in the Bengaluru ODI?

Team India players are wearing black armbands in the ongoing third and final ODI against Australia in Bengaluru. This is in tribute to former all-rounder Bapu Nadkarni, who passed away aged 86 on Friday. Nadkarni was best known for bowling 21 maiden overs in a row in a Test match in 1964, which is still a world record.