This week's four remaining celebrities face three more culinary challenges as they fight for a place in the quarter-final.Tonight's first challenge is a Knowledge and Skills Test, where the celebrities have the terrifying task of facing judges John Torode and Gregg Wallace one on one. They attempt to demonstrate their ability by making fettuccine with basil and parsley pesto in just 15 minutes.Next, the celebrities are pushed to their limits. Up until this point in the competition, they have been cooking food as they would at home, but to show them what restaurant-standard cooking is all about, John and Gregg have invited in professional chef Freddy Forster. Winner of the prestigious Roux Scholarship in 2000, Freddy has spent his career working in some of the world's best kitchens, including The Savoy, Le Manoir aux Quat'Saisons, L'Aubergine and Pierre Gagnaire in Paris. He challenges each of the four celebrities to cook a recipe that combines his classical cooking technique with flavours inspired by his West African heritage.Then it's crunch time as there's just one more chance for the four celebrities to earn themselves a place in the quarter-final. Their brief is to cook a dish that's full of nostalgia - a dish that tells John and Gregg something about them growing up. With just one hour to cook and only three quarter-final places up for grabs, the celebrities give it their all in a final attempt to prove themselves to the judges. At the end of this test, one of them will be going home.