"A Snake in the Grass, Part 1", known as "Decisive Battle! Judai VS Professor Cobra" in the Japanese version, is the one hundred and seventeenth episode of the Yu-Gi-Oh! GX anime. It first aired in Japan on January 3, 2007 and in the US on September 1, 2007
Axel finally manages to escape from Viper's trap. With both Mr. Stein and Trapper defeated, Jaden and Jesse are both exhausted. Both argue slightly about which direction to go. Jesse wants to go forwards a take on Viper; whereas Jaden, concerned about his overconfident friend, wants to go back and find the others. In the end they agree to stay put and wait for the others to come. Jaden and the gang then reunite, infiltrating Viper's lair. While doing so, Adrian meets up with Viper in order to take a particular card for the Gecko Family, pressing a hidden button in his deck box to short circuit yet another security system. This leads to the doors closing in on Jaden and the gang, so they ran further into the lair before all the doors closed.
Adrian then tells Viper that his duel with Jaden has been postponed, suggesting that he and Viper do a different kind of duel, without using the Bio-Bands (In the Japanese version, Adrian suggested to make Viper hand over the card by force). Viper accepts the challenge, stripping down to his trousers in an attempt to intimidate Adrian with his physique. Unfazed by the intimidation attempt, Adrian tells Viper that despite how he may appear, he has confidence in his strength, stripping before engaging in a fist fight with Viper, to which the former is flung into a wall by the latter. After Adrian avoids another one of Viper's attacks, the latter says that he knows the former is associated with the Gecko Financial Group.
The scene then cuts to Axel assisting the gang in overcoming another trap. Unfortunately, Axel had to sacrifice himself by leaving himself behind while the rest of the gang continue their infiltration. It then cuts back to Viper mocking Adrian about his position as a member of the Gecko Group, angering the latter into throwing an office chair at the former, continuing the fist fight. Adrian then mocks Viper about his old age and slow moves, saying that this is how a retiree like Viper differs from an active worker like the former, (in the dub, Adrian once more tells Viper to give him the card). before the Devil Arm equips itself onto the latter, preventing the former from landing one last punch.
Adrian is then paralyzed by the demon in the tank. After passing several traps with Axel's help, Jaden and the others finally meet Viper. While Axel stays beind and his fate is unknown, Viper and Jaden engage in a Duel. Although starting out enthusiastically, Jaden is quickly driven back by the weakening effects of Viper's Venom Deck.
Adrian is still trapped in the room where he met Viper, and the Duel Monster Spirit in the tank begins to attempt to convert him to it' side. It brings back memories of his childhood. After he was adopted by the Gecko Family, he trained himself both physically and mentally to be a worthy heir. However, once the Geckos had their own biological son, Shido, he began to be ignored by his parents. Only Echo still remained by his side.
Turn 2: Viper Viper draws. He then Normal Summons "Venom Snake" (1200/600) in Attack Position. Viper then activates the effect of "Venom Snake" to place a Venom Counter on "Elemental Hero Clayman" at the cost of forbidding "Venom Snake" from attacking this turn.
Viper then sets two cards and activates "Venom Swamp". Now all monsters on the field will lose 500 ATK for each Venom Counter that they have on them ("Clayman": 800 → 300/2000). If a monster's ATK is reduced to 0 by this effect, that monster will be destroyed. During each player's End Phase all face-up non "Venom" monsters will have a Venom Conuter" placed on them.
On Viper's End Phase, "Venom Swamp" places a Venom Counter on "Clayman" ("Clayman": 300 → 0/2000). The third effect of "Venom Swamp" then activates, destroying "Clayman".
When Adrian prepares to battle against Viper, the former's headset, cloak, deck box and belt are dropped in front of his feet. In the following scene after Adrian strikes a pose, the aforementioned items disappear.
In the Dub, after Jaden refuses to drink the water, Syrus breaks the fourth wall by mentioning he was carrying it for three episodes.
The following cards appeared in this episode. Cards in italics debuted here.