head-to-head

(hĕdˈtə-hĕdˈ)

1. In direct confrontation or conflict at close quarters: The two brothers went at it head-to-head. It was a head-to-head contest all the way.
2. Arranged in a line with the heads adjacent to each other: The bunk beds were set up head-to-head.
3. Running close together in the same direction; neck and neck: The horses ran mostly head-to-head.