It's the final week of the heats, and tonight four more chefs don their MasterChef whites to confront two demanding tasks. Those that hit the MasterChef standard might just find themselves in the last quarter-final.Marcus gets things underway as he challenges the first two contenders in a tricky skills test. On order today is pan-fried plaice, a beurre blanc sauce and shoestring fries. The professionals have the ingredients to hand, but they will need know-how to succeed in this daunting challenge.The next two chefs have 20 minutes to tackle Monica's test - perfectly cooked lamb neck, served with a pea and broad bean puree, a lamb sauce and charred leaks. A grasp on classic techniques will be needed in this task, which is sure to put them through their paces.The four who survived the first challenge will come together for the signature round – two courses that knock the socks off the judges, and point to a chef with true potential. Anything less could mean it's game over.Only the strongest chefs on the day can head into the quarter-final, where the pressure ramps up, and the race for the title well and truly begins!