The singing competition gave BBC One an average of 8.50 million viewers during its 7.15pm - 8.30pm slot, taking 36.6% of the audience share.
Over on ITV, Tom Daley's Splash! continued with a slight increase in viewers from last week at 6.45pm, with 3.62m (16%) tuning in to see Perri Kiely and Keith Duffy make it through to the final of the diving competition.
Back to BBC One, National Lottery: Who Dares Wins entertained 5.89m (26.6%) at 8.30pm, while the latest episode of medical drama Casualty had 5.20m (24.1%) gripped at 9.20pm.
BBC Two's biggest primetime ratings came from Dad's Army at 8pm, with 1.94m (8.2%) tuning in to the wartime sitcom. 2010 comedy film Made in Dagenham brought in 1.22m (5.9%) at 9.15pm.
ITV's Take Me Out attracted 3.28m (14.6%) at 8.15pm,