How to Win Connect 4 as Player 2 (Going Second)

The Hard Truth, Then the Good News

Victor Allis and James Allen both showed in 1988 that Connect 4 is a first-player win when Player 1 opens in the center column. There is no Player 2 strategy that beats a perfect center opening — the best you can do is draw, and only with exact play. That is the math.

The good news: almost nobody plays perfectly. Most opponents drift off the optimal line within five moves. Some open on the edge and hand you a forced win on move one. Once you know what you are looking for, the wins as Player 2 come fast and often.

When Player 1 Opens Center (Column 4)

This is the only opening you cannot beat with perfect play. Your job is damage control.

The cleanest defensive plan: stack on top of Player 1 in column 4. This claims the second row of the most valuable column and forces Player 1 to break symmetry. From there, mirror their column choice across the center axis. If they play column 5, you play column 3, and so on.

Look for chances to convert defense into an even-row threat. If Player 1 stacks aggressively in one column, you can sometimes get a row 2 or row 4 four-in-a-row that they cannot block without giving you a different win. Even against a perfect P1, sharp even-row threats can earn the draw and occasionally the win when they slip.

When Player 1 Opens Adjacent (Column 3 or 5)

A common amateur opening. The right response is to take the center yourself. Now you own the most valuable column and Player 1 is sitting on the second-most-valuable. From here you build the standard center-stack diagonal attack.

With correct play this leads to a draw. In practice it leads to a Player 2 win more often than not, because the position favors the side that knows the plan, and most amateurs do not.

When Player 1 Opens an Edge (Columns 1, 2, 6, or 7)

Free win. This is the single highest-value pattern to memorize as Player 2.

Take the center. Player 1 is now far away from the most important column on the board, with no way back without losing tempo. Stack the center on your second move if Player 1 does not contest it. Build even-row threats on both sides. Within ten moves you will have multiple unblockable threats and the game ends.

Edge openings happen surprisingly often in casual play, especially from players trying to "be tricky" or avoid the obvious center move. Reward them.

The Even-Row Threat Principle

Player 2 plays the second, fourth, sixth, and eighth stones in any column where both players keep stacking. That puts Player 2 on even rows (2, 4, 6 from the bottom). A threat that completes on an even row cannot be blocked by Player 1 just stacking — they would hand you the four-in-a-row on your next move. Player 1 has to either play elsewhere (giving you the win) or build a counterthreat fast enough to ignore yours.

The whole Player 2 plan is: build defensive shape, wait for Player 1 to commit, then create one or two even-row threats that they cannot answer. Stack the center, defend the diagonals, count parity on every potential four-in-a-row.

The Undercut Rule

When Player 1 has built a stack with an unfilled column under it, sometimes the right move is to play the column directly below their stack. This "undercut" gives them a free piece on top, but it forces them onto a row whose parity you control. You give up a tempo to fix the parity of every future threat in that column. Use it when you can see that the current parity loses you a key threat that the undercut saves.

What to Do Next

The deeper version of this material lives on the best Connect 4 strategy going second page, which covers the four strategic regimes (center, adjacent, edge, outer) in tighter detail. To understand the attack you are defending against, read the Player 1 win guide. Then drill positions on the engine until the parity check happens automatically.