Petrov 1958/59

The first move is obvious: 1.Rd8!
However, after the best reply 1...a2! the win is still unclear.
2.Bxa2 Rf4+ 3.Ke3 Ra4 4.Bb3 Rb4.

It seems that White can't save both his bishops in the same time. But, as a bombshell, there follows an amazing final...