The slick BBC1 spy saga is moving from its traditional Monday night slot for its final series, to be pitched against ITV1's period phenomenon.
Spooks, starring Peter Firth as an MI5 boss and Lara Pulvey as a new recruit, is being axed after the forthcoming tenth series.
Both shows begin on Sunday September 18, at 9pm, according to newly released schedule details.
The hotly-anticipated second series of ITV1's Downton Abbey will explore how the lives of the residents and staff of the titular estate are affected by the First World War.
Julian Fellowes' period drama counts Dame Maggie Smith and Hugh Bonneville among its cast .
A BBC spokeswoman played down the potential ratings battle, saying: "Downton and Spooks are very different shows and offer a real alternative for audiences.
"This is the last ever series of Spooks and we wanted to celebrate this and make it a special event for viewers in the Sunday 9pm slot.
"It is not unusual for drama to go up against drama here, for example, David Tennant's Single Father did last year and ITV1's Vera was up against BBC One's Exile earlier this year."