Flush on the Board? Turn These Tricky Spots Into Profit

Buckle up, poker strategy nerds. This one’s for you.

5-to-a-flush boards (like AdQd9d6d2d) are rare but fascinating from a theoretical perspective.

Even top players make mistakes here. I’m going to break down key solver takeaways, plus share some real-world advice to sharpen your game.

Let’s dive in!

Note: This article requires knowledge of the following concepts: Ranges | Game Theory Optimal (GTO) | Solvers | Mixed Strategies

For introductory and intermediate articles, check out Upswing Poker’s article library here.

What Makes Boards with a Flush Special?

These boards are unique because even the weakest hands make a flush. As a result, traditional hand categories dissolve, leaving both players with either a higher flush or a hand that plays the board.

Here’s an example to illustrate:

• The Button (BTN) raises, and the Big Blind (BB) calls.
• BTN c-bets the flop (33% pot), and the BB calls.
• The turn checks through, and action is now on the BB.
• The board: Ts8s2s5sQs.

Check out what the equity distribution looks like:

The X-axis represents the percentile of each hand within a player’s range (based on equity vs. the opponent’s range), while the Y-axis represents the equity of each hand.

Both players’ ranges show a long, flat line due to the 5-flush runout, which erases traditional hand class distinctions. However, the in-position player (red) has a longer flat line, meaning the out-of-position player (green) holds more flushes.

We’ll explore this dynamic later!

How To Play 5-Flush Boards

With countless board textures, preflop sequences, and postflop lines leading to 5-flush boards, mastering these spots could fill an entire book. Instead, I’ll break down the key thought process you need by analyzing a few of the most common scenarios.

Example #1: The flop and turn go check-check

A common scenario is when the BTN open-raises and the BB calls. The board runs out As8s5s. The BTN checks back, the turn brings the 9s, and both players check again. The river comes the Js.

Most hands will play passively here, and for good reason—both players retain a similar number of flushes throughout the game tree. This balance reduces the incentive for aggression.

Now, let’s examine the equity distribution in this spot.

As shown in the graph, we again see a long, flat line—this time even longer than in the first example. The reason is that by this stage of the hand, both players have already bet a portion of their flushes, while weaker hand categories have mostly checked.

A key difference is that the top percentiles of both ranges overlap significantly. This means that the distribution of nutted (or near-nutted) hands is symmetrical.

Because of this symmetry—and the fact that the BB is out of position—we should expect the BB to adopt a very passive strategy. This approach is necessary to protect the middle of their range.

As a result, we also anticipate that the BB will use smaller bet sizes, avoiding overbets. And sure enough, this is exactly what we see from the Solver:

The BB checks with the vast majority of their range, including a significant portion of both the nut and second-nut flushes.

If the BB fails to check enough strong hands, the BTN can exploit this by increasing their bet size when checked to and bluffing more frequently.

In this scenario, traditional hand classes become nearly irrelevant in terms of their blocker effects—every hand type bets at some frequency. The Solver balances this to avoid creating an exploitable pattern that the BTN could use for bluff-raising.

It might be tempting to assume that any strategy here is equally viable, but that would be a mistake. When we examine the BTN’s counter-strategy against a 75% pot bet, things get interesting:

I filtered out all hands that contain a spade, and we still see the same pattern—raises are evenly distributed across all ‘hand classes’ (which are now all flushes).

Now, think back to the last time you were in a similar spot. Did you even consider raising a hand like a pair? If you’re like 99.999% of players, the answer is probably no.

If opponents aren’t bluff-raising enough, bluffing from the BB generates more EV than the solver assumes—since the BTN isn’t applying enough pressure.

Example #2: The flop goes check-bet-call and the turn checks through

Let’s revisit the scenario from earlier: The BTN raises, the BB calls, and we reach a 5-flush board after a flop c-bet and a turn check-through. The board is Ts8s2s5sQs.

Here’s the equity distribution again, but this time, let’s analyze what it really means for both players’ strategies.

Unlike before, this scenario shows a clear power shift. The BB has a significant equity and nut advantage, as evidenced by the green line dominating the top 40% of hands.

This happens because the BB’s range has already been strengthened by calling a flop c-bet and folding out weaker hands. Meanwhile, the BTN’s turn check signals a lack of strong flushes, further solidifying BB’s advantage.

With such a dominant position, the correct strategy for the BB should be highly aggressive. And that’s exactly what the Solver prescribes:

Few players outside the poker elite employ this strategy. But it’s a pattern you should look out for and apply when possible.

Now that we’ve established the BB’s optimal approach, let’s shift our focus to the BTN. How should the Button adapt when facing this relentless aggression?:

We are in a bizarro world at this point. Folding Tx and 8x hands, but calling with air? It makes perfect sense! Let me explain!

After the range filtering that occurred on the flop, the BB won’t have many “bluffing” hands left on this runout. Thus his “bluffs” become Tx and 8x hands. When bluff-catching, we want to block the value hands (impossible in this scenario, because every hand is a flush) and unblock the bluffing hands.

When the BTN holds Tx or 8x, he blocks the bluffs. There is a small equity shift that occurs, where the BB ends up having slightly more flushes compared to when he isn’t blocking those Tx and 8x hands.

Final Thoughts

I hope you found this short but powerful guide insightful in navigating the tricky yet fascinating world of 5-flush boards. By applying these principles consistently, you’ll gain a much deeper understanding of these rare spots and be able to exploit them at a high level.

That’s it for this article! Let me know in the comments — do you approach these situations differently? Have you spotted any unique exploits in your games? I’d love to hear your thoughts!

If you’d like to learn more about playing profitably in uncommon lines, read: 3 Profit-Creating Tips for Delayed C-Betting (via Lucid Poker).

Till’ next time, good luck, grinders!