When sportsbooks made opening lines on the NFL's Week 1 games in early May, the Kansas City Chiefs were 6.5-point favorites against the Detroit Lions. In nearly four months after the line was released it moved once, to Chiefs -7 for a few days in August. Then it went back to Chiefs -6.5, where it stayed.

Until Tuesday. Then it moved again after some major news.

When news broke that Chiefs all-world tight end Travis Kelce had hyperextended his knee and his status for Thursday's game was in doubt, the line moved to Chiefs -6 at BetMGM. If Kelce is out for Week 1, that line is likely moving again and off of -6, which is an important number in football betting.

How much is Kelce worth to the line? Perhaps we'll find out, though he has not missed a game since his rookie season of 2013. If there's no ligament damage and just pain management, it seems likely Kelce will try to play. But we don't know, and we don't know if Kelce will be effective two days after hurting his knee.

Kelce's injury makes for two potential massive absences for the Chiefs, one on each side of the ball. Defensive lineman Chris Jones, easily the Chiefs' best defensive player, has been holding out. Chiefs coach Andy Reid said Tuesday there has been no progress in talks with Jones, making it very unlikely Jones would be suiting up and playing a full game by Thursday.

The Chiefs rely on Kelce more than any other team relies on its tight end. Kansas City doesn't have a standout No. 1 wide receiver, so Kelce has been Patrick Mahomes' primary target. His absence in the Chiefs' offense can't be overstated.

If Kelce is out of the lineup or more news develops on the extent of his injury, the line could move again. It's unlikely any other tight end being out would move a point spread. Just the possibility that Kelce could be out has already moved the Lions-Chiefs line for Week 1.