The Judges' House phase continues, with the acts jetting off overseas to perform for their mentors in the hope of winning a place in the live shows. Each coach has a guest judge on hand to help them - Louis Walsh and Mika assess the boys in Istanbul, Simon Cowell and Cheryl teach the groups in France, Nicole Scherzinger and Stormzy take the overs to South Africa, and Sharon Osbourne is joined by her children Jack and Kelly to oversee the girls in San Francisco.