An offensive formation in football which features a single running back positioned about five yards behind the quarterback. The standard formation uses two wide receivers and two tight ends.
The single set back formation (also known as the “Single-back,” “Ace,” “Lone Setback,” “Solo,” and “Oneback”) formation is common in modern college and professional football offensive schemes. It is primarily used to attack zone and advanced defenses, utilizing one running back and four receivers in order to force the defense to choose between the pass or run. Tight ends can receive passes or provide run blocking, while the running back can take a handoff from the quarterback, run to the flat as a receiver, or hang back to help block pass rushers.
There are many variations to the single-back, using any combination of wide receivers and tight ends. For instance, the Single-back 4WR formation uses four wide receivers that line up in a spread pattern, while the Single-back Ace uses two receivers and two tight ends who line up to either side of the tackles. In either case, the defense has to worry about multiple threats, primarily because the ends and back can become passing threats if necessary. Requiring an immense amount of athleticism and intelligent play, the single-set back is most popular in the NFL.