The final four of the sixth season of "MasterChef US" is set and they will need to "Think Inside the Box" for this week's episode. Claudia Sandoval, Derrick Peltz, Nick Nappi and Stephen Lee will have to out-cook each other in the kitchen to avoid the elimination challenge and be part of the top three.

In last week's episode titled "Return of the Champions," former MasterChef winners from seasons three, four and five helped during the elimination challenge. Christine Ha, Luca Manfe and Courtney Lapresi were present as they selected additional ingredients that were used in last week's elimination challenge, as reported by International Business Times.

In the same report, Katrina Kozar was sent home after serving a raw veal scallopini and her tagliatelle dish was not enough to save her from elimination. Nick, Stephen and Derrick survived the elimination that involved ingredients chosen by the last three "MasterChef US" champions and Claudia, who won the Mystery Box challenge.

According to TV Guide, this week's episode titled "Think Inside the Box" has a synopsis that reads:

"The Top 4 cooks pair off to create an appetizer and an entrée-and then repeat it twice-using ingredients provided by judges Gordon Ramsay and Graham Elliot. The winners advance to the Top 3, but the losing team compete in the next pressure test, which involves preparing judge Christina Tosi's chocolate-malted layer cake."

The official Twitter account of MasterChef on FOX posted an episode promo showing the pairs disagreeing. Gordon Ramsay and Graham Elliot is set to present a list of ingredients that will be used to cook an appetizer and an entrée, and the contestants will have to cook the dishes twice.

In the promo, rivals Stephen and Derrick will form the blue team while Nick and Claudia will pair up to be the red team. During the 90-minute pressure test, the contenders are set to make Christina Tosi's chocolate-malted layer cake that is said to have been perfected in six months.

In a separate report from the International Business Times, Stephen and Derrick have a big rivalry and have targeted each other's backs, but they also won the tag team challenge earlier in the season. FOX also uploaded a video on their official YouTube channel, which shows some deleted scenes on episode 18. You can view the video below.

In the video, Derrick and Stephen are standing in the balcony, presumably safe, while Nick and Claudia are wearing black pressure test aprons in front of the judges that are messing their lines and cursing.