Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bb5/3...a6/4. Ba4/4...Nf6/5. O-O/5...Nxe4/6. d4/6...exd4/7. Re1/7...d5/8. Nxd4

=Ruy Lopez:Riga Variation=

Both Nxc6 and f3 are now threatened, and even if Black can meet the first threat there seems to be nothing she can do about the second, unless she can distract White by going after something more valuable than a knight. The departure of the f3-knight, an important defender of the White kingside, along with the strong placement of Black's own knight on e4, might be a clue...

The move is 8...Bd6, and the plan is for Black's bishop, knight and queen to have a chat with the White king.