Defending 3×1 Formations – Solo Coverage

Kick the coverage with out the spin.

The biggest issue facing defenses when defending 3×1 formations is the run/pass conflict of the Mike. No other player in a 3×1 formation has more on their plate than the leader of most defenses. In modern football, the age of a “plugger” at Mike is over. Each LB must be able to cover underneath routes and understand how their run fits relate to their pass drops. Defenses can no longer afford to drop their LBs to “zones” or landmarks. Each player is a link in a chain. As the spread becomes a permanent fixture in most regions’ football cultures, defenses are turning to match schemes to help alleviate the issues seen in traditional defenses.

Traditionally, teams have spun to the three-receiver side to allow the Mike to stay in the box, switching his responsibility of relating to the #3 receiver to “plugging” the middle of the formation. Eliminating this run/pass conflict helped defenses against the “spread-to-run” offenses but it opened them up to high percentage throws that could easily become fatals (TDs) when those offenses ran play -action. In the diagram below, an Over Cover 3 scheme is shown:

.99 C3

Right away, the main issue with Cover 3 or “kick” coverage to Trips is the backside corner is in man-to-man coverage with the single WR. Offenses traditionally have left their best receiver at the “X” because of this defensive scheme. The best offensive receiver on the field is lined up across from a player with little to no help. This can spell disaster for defenses. As the spread as evolved, offenses have developed reads for the third level. If a defense spins to a 3×1 formation (“kick”) the offense can easily check to a backside choice route depending on the leverage of the corner. For most, this is a post route ran right off the back of the kicking safety. This is a high percentage throw that can spell disaster for defenses. 

One way to combat the multitude of spread offenses is to stay in a two-shell, or two safety look. This allows the defense to stay evenly distributed. The key to defending the spread is in the numbers and cover downs. A defense wants to have a plus-one in the run game and versus the pass. This can be accomplished in a two-high shell. The backside safety versus any 3×1 set is technically the new Will LB. To ease the backside safeties conflict against the run modern defenses have shifted the front from Over to Under when defending 3×1 formations. This slight adjustment allows the boundary safety to fit outside the box and gives the Mike a better cover down to the #3 WR. By running an Under Front, the defense also gains cover downs to the #2 and #3 WRs. Even though the Mike is still in conflict, his path is shortened and if playing a zone team, his gap can be easily exchanged against a zone play away. This gap exchange allows the Mike to “hang” in his zone. Here is an example of the run fits out of Under:

v. Under

Most offenses don’t base out of a four vertical offensive scheme. Spread offenses utilize simple screens, West Coast, or Air Raid (over/crossing route) principles in their offense. Using the law of averages a defense can reduce Mike’s conflict and steal a coverage player to the front side, all while keeping a two-high shell. This example of hybrid coverage can only be done out of a split field defensive scheme. As defensive coaches figured out that offenses would not run four verticals every play, they turned to Solo coverage.

Solo Coverage

.01 Solo v 10p

Where Cover 3 leaves you vulnerable to the backside post (high percentage throw), Solo coverage leaves a defender in the middle of the field while shifting the frontside coverage to three defenders over two receivers. In the diagram above, the backside safety (DS) is stepping off his initial alignment and keying the #3 WR. If the WR takes off on a vertical route the safety will “kick” to “top” the route. The DS’ step-off is the same as if he was in Sky coverage, being patient and reading his key (the #3 WR). The Mike can “hang” in his position because he does not have to fly out to match the vertical of #3. The boundary CB is locked on to the backside WR but will release any unders to the Will LB. Sticking with typical match quarters rules, the Mike will always relate to the #3 receiver and the Will always relates to the #2 weak receiver.

To the front side, the defense has gained numbers on the outside WRs and run their coverage much like they would against a traditional 2×2 set. The frontside safety (CS) can run a Sky (4-Read) or Cloud (2-Read) concept to combat the alignment and route combinations of the two outside receivers. Solo coverage allows the defense to steal a coverage man frontside without opening the door backside. If the #3 WR runs anything other than a vertical route the defense morphs back into typical quarters and the DS squares up and looks for help over the middle. One great thing about Solo is the DS becomes a centerfield player creating a double alley defender. Once the DS has determined the play is a run he can attack the flow of the offense. This can give the defense even greater numbers to the front side if the play goes to the Trips side. Here are examples of Solo pass distributions:

Solo vs Four Verticals

.02 (10p) 4 verts

Solo vs Pick/Flat

.03 (10p) Pick-Flat

Defending Trey or TE Trips

.04 Solo v 11p

Where Solo really earns its stripes is against a Trey formation or TE Trips. There is a tendency by defensive coaches to spin when an offense either adds a back to the backfield or a TE to the line. As stated prior, the modern spread offense wants the defense to spin. This creates one-on-one matchups and leaves the backside CB in a major bind. The best way to stay in a two-high shell without locking the Mike on the TE in Trey is to run Solo. This keeps the DS in the backside run fit and allows him to hold the intermediate (underneath) zone against a backside post.

It is still in the best interest of the defense to align in an Under Front to Trey. This combats speed option and leaves the DS as the plus-one to the backside. Solo can be great against teams that use play-action to suck the LBs in only to throw a “pop” pass to the TE over the middle. Unlike versus Trips, the DS has less ground to cover and can be a realistic added value to the backside. Take a look at the Solo pass distribution against Trey:

Solo vs Y-Pop

.05 (11p) Y-Pop

Solo vs PAP (Comeback/Bender)

.06 (11p) PAP (Cob-Bender)


  1. Widen the backside DE: Once offenses figure out that a defense is running Solo they can easily use the vertical of #3 against them by running stretch or Buck Sweep (stretch with pulling guards) to the backside. The DE to the boundary has to widen from his normal five-technique to be able to combat the pull. He also has to box any puller. In most cases, the DE spills and the LBs box, but because the DS is “kicking” with any vertical by #3, the DE has to box and force a cutback to the rallying players in the box. Their roles reverse.
  2. Inverted Flood Route: One way an offense can affect Solo coverage adversely is by running an inverted flood route. This route switches the flat route from the traditional #3 WR to the #2 receiver. The switch plays on the frontside safety’s rules for Sky or Cloud coverage. If a defense is running Cloud (2-Read) to the front side the CB will drive on the flat and the CS will top the fade. This leaves the intermediate zone naked. If this is the case, the Sam will actually have to attempt to work under the sail route by #3, this is an awkward situation for the defense. The CS to the front side needs to keep an eye on the #3 WR running off his backside.
  3. Backside Vertical Routes: If a defense’s boundary CB is not strong, an offense can easily attack the defense by running a backside choice route to the boundary. As stated in the first issue, offenses can play with the read of a Solo DS by running a vertical with #3. The DS has to be patient enough to top the route by #3 while keeping an eye out for the backside post. If offenses utilize the backside WR it is better for the defense to run Stress or Special to maintain an extra defender over the “X.” In Solo, the risk is reduced but not completely eliminated. It is the DS’ responsibility to hold the middle zone while working to top #3. Many times the #3 WR works to the opposite hash or bends into the middle of the field in a four vertical play. This fact can help the DS be patient.


Teams that have a great boundary CB or are facing a team that throws heavily to the three-receiver side can utilize Solo and gain an advantage. Where Solo can become deficient is against 10 personnel spread teams that use width to play with the boundary safety. Solo truly earns its stripes versus 11 pers. Trey. Against Trey, Solo can be used to combat “pop” passes and allows the Mike to be aggressive in the box. The biggest dilemma versus any 3×1 set is how to defend the #3 WR. To keep from spinning a defensive coach can use Solo to eliminate conflict and steal a coverage player to the front side. The DS is still a centerfield player, as he would be in Cover 3, but the defense isn’t showing its cards early and it can be more flexible against the modern spread.

© 2017 | Cody Alexander | All rights reserved.

Looking for more 3×1 Resources? Find them here:

  1. Why an Under Front to 3×1 Formations:
  2. Top Trips Coverages Explained
  3. Defending Trips with Stress
  4. Defending Trips with Special

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Author: MatchQuarters


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