If you're making a list of players the Colts can't afford to lose to injury - besides Andrew Luck, of course - Ryan Kelly is probably near the top of the list.

The second-year center, who had a very promising rookie campaign last season, left today's Training Camp session and did not return. The Colts haven't specified what the injury is, but longtime beat writer Mike Chappell reported this:

The question now is, what is a "few" weeks? You would think that means four or less, which would obviously make Kelly available for the regular season opener in Los Angeles.

If Kelly misses any more time than that, the Colts are in trouble. The current backups are Deyshawn Bond, an undrafted free agent from Cincinnati, and Brian Schewenke, who is on the PUP list. Yikes.