Russert died of a fatal heart attack last week at the age of 58.

The Washington Post (NYSE:WPO) said Williams, Russert's longtime friend and a former White House correspondent, will take over for Russert for Sunday's show. His guests will be Sen. Joe Biden, D-Del., and Sen. Lindsey Graham, R-S.C.

The network is still reeling from Russert's death and has not made a decision regarding who will permanently replace him on "Meet the Press," the Post said.