With my opponent having taken the center position (1,1), I'll place my first O in the top-left corner (0,0). This is a strong counter to a center opening because:

1. It establishes my presence on one of the diagonals, which is a key winning line.
2. It gives me potential winning opportunities along the top row and left column.
3. By taking a corner rather than an edge position, I maximize my strategic options for future moves.
4. This prevents my opponent from creating an easy fork situation where they could set up two potential winning lines simultaneously.

Taking a corner is generally considered the optimal response when the first player takes the center in Tic-Tac-Toe.