In the middle of the Detroit Lions’ win over the Indianapolis Colts, there was one of the most odd sequences you’ll see from an offensive line standpoint.

After a knee and ankle injury temporarily knocked Lions left tackle Taylor Decker out of the game, Detroit had to adjust on the fly and they did so in an extremely unexpected fashion. Instead of just plugging in Dan Skipper at left tackle—as they’ve done countless times before—they moved left guard Graham Glasgow to left tackle and brought in Michael Niese to play left guard. It was Glasgow’s first-ever snap at left tackle, and it only lasted a single snap. After that play, the Lions went back to their expected lineup: Glasgow back at guard and Skipper at tackle

So what the heck happened?

Justin Rogers of Detroit Football Network got the scoop, talking to Glasgow after the game.

“Skip reported as eligible the play before, so you can’t come in the next snap as an ineligible player unless you call a timeout,” Glasgow said. “I don’t even know what was happening. They were just yelling on the sidelines and they just said, Play left tackle for a play.’”

Indeed, on the play of Decker’s injury, Skipper reported as an eligible receiver (and coincidentally allowed the pressure that caused the Jared Goff sack and collision that injured Decker). And it’s spelled out blatantly in the rulebook—Rule 5, Section 3, Article 2—that when a player changes his eligibility from eligible to ineligible one of nine things needs to happen between those two occasions.

ARTICLE 2. RETURNING TO ORIGINAL POSITION. A player who has reported a change in his eligibility status to the Referee is permitted to return to a position indicated by the eligibility status of his number after:

(a) a team time out;
(b) the end of a quarter;
(c) the two-minute warning;
(d) a foul;
(e) a replay review;
(f) a touchdown;
(g) a kick from scrimmage;
(h) a change of possession; or
(i) the player has been withdrawn for one legal snap.

Penalty: For a player failing to notify the Referee of a change in his status when required, or an offensive player with an eligible number reports as ineligible and lines up outside normal five-player core: Loss of five yards for illegal substitution.

It seems a little silly that an injury timeout isn’t on this list of possible options—particularly when it impacts a team’s ability to substitute the player they want for an injured player—but the Lions did have another option within their control. They could have called a timeout, but at that point in the game—a 14-6 contest midway through the third quarter—they didn’t want to burn one.

So, instead, offensive coordinator Ben Johnson called a play that would minimize the impact of the mixed up left side of the offensive line: a quick RB screen to Jahmyr Gibbs the right that went for 4 yards.

“There was a little bit of chaos going on in the huddle, trying to figure out who was where,” Goff said after the game. “I think Ben called a screen, which made it easy for the backside of the play. They knew what they were doing, and then Skipper came in and we went on from there. But yeah, our guys settled in nicely once that happened. It was a little bit of chaos for a second, yeah.”

In the end, no harm, no foul, and a fun quirk for Glasgow’s career. Now he needs to just log a snap at right tackle to be able to say he’s played literally every offensive line position.