The first week of heats continues as the four remaining celebrities face three more culinary challenges, battling for a place in the semi-finals. The first challenge is a relay invention test, and it's all about teamwork. Split into two teams, each team must create a main course and a pudding between them, using a guineau fowl for the main and tropical fruits for the pudding. Each team member has 25 minutes to make their contribution to the dishes, but they can't communicate with one another, so each cook must try and work out what the dishes are meant to be from the clues left behind by their teammate, and then carry on. For the final 15 minutes, the team members come together to finish the dishes, but will the celebrities be able to create something successful? Next, the teams are sent out on their first mass catering challenge. They have to make lunch for over 100 members of staff at the Emirates Stadium, home to Arsenal Football club. The two teams must devise, prepare and serve the lunch, catering for various tastes while creating meat-based, vegetarian and dessert dishes in volume. As the battle for a semi-final place reaches its climax, the four celebrities must now cook a faultless two-course meal that will not only be judged by John and Gregg, but also by past Celebrity MasterChef champions Sophie Thompson (2014), Emma Kennedy (2012), and previous finalist Wayne Sleep (2014). Only the best two contestants can earn a semi-final place and come one step closer to winning the title of Celebrity MasterChef 2015. For those who don't make the grade, the journey ends here.