Further , a particular extra move is sometimes more of a liability than an asset . For example , Soltis notes that the Exchange French position arising after 1.e4 e6 2.d4 d5 3.exd5 exd5 4.Nf3 Nf6 " is pretty equal . " The same position , but with Black 's knight moved to e4 , arises in Petroff 's Defense after 1.e4 e5 2.Nf3 Nf6 3.Nxe5 d6 4.Nf3 Nxe4 5.d4 d5 . That position offers White better chances precisely because Black 's extra move ( ... Ne4 ) allows the advanced knight to become a target for attack .