How to Win Going Second

The Player 2 Mindset

Going second in Tic Tac Toe (usually playing as O) is widely considered a defensive battle. Because Player 1 (X) controls the pace of the game, your immediate goal is to prevent them from winning. However, you can absolutely win going second if Player 1 makes a mistake. To do so, you must play defensively and bait your opponent into errors.

How to Defend Against the Corner Opening

The most common opening move for Player 1 is to take a corner. If they do, your response must be exact:

The Golden Rule: You must take the center square. If you take any of the edges or other corners, Player 1 can place their second mark to set up an unavoidable fork, and you will lose the game.

Once you take the center, Player 1 has two choices for their second turn:

• They take the opposite corner: You should take any of the four edge squares. This blocks their line and sets up a draw.
• They take an edge: You must block their threat immediately. If they make a mistake in their blocking placement, you can counter-attack.

How to Counter the Center Opening

If Player 1 starts by taking the center square, your best response is to take a corner square. Placing your symbol on an edge is a critical error; it allows Player 1 to place their next symbol in a corner, setting up a winning diagonal line that you cannot block. By taking a corner, you limit their angles of attack and can easily guide the board to a tie.

Exploiting Player 1's Mistakes

Many casual players do not know how to handle center-defense. If Player 1 starts in a corner, you take the center, and Player 1 plays an edge on their second turn, they have surrendered their advantage. You must identify if they have left any open lines, block their secondary threats, and look for opportunities to place two of your symbols in a row to force them into a defensive role.

Step-by-Step Defense Walkthrough

Here is how a perfect defensive sequence plays out when going second:

1. Move 1: X plays in the top-left corner (cell 1).
2. Move 2: O responds by occupying the center (cell 5).
3. Move 3: X plays the opposite corner (cell 9), hoping to bait a corner response.
4. Move 4: O plays the top-middle edge (cell 2) to block and force X to defend, guaranteeing a draw.

Defensive Practice: Solve the Puzzle

Test your Player 2 defense! In the challenge below, Player X has opened with a corner move. Find O's only correct response to avoid a forced loss.