Chargers HC Mike McCoy says WR Keenan Allen (knee) was sent to athletic trainer's room midway through practice to get treatment.

He had knee problems in Cal, so this is something to monitor during camp. Allen is in line to be the WR3 or WR4 for the Chargers depending on the status of Malcom Floyd (sprained knee). At this point the rookie is only worth a late-round flier.

Rookie Keenan Allen is playing catch-up. A damaged posterior cruciate ligament (knee) cost him his final three games at Cal last December, and Cal's class schedule denied him a few practices at Chargers Park in May.

Allen, 6-foot-2 and 211 pounds, said the knee was "85 to 90 percent" of full strength in June and "close to 100 percent if not 100 percent" when training camp opened July 25. He's made all 11 practices. Sometimes, he asserts himself. Other times, he looks uncertain. The four exhibition games represent a big chance for him to earn McCoy's trust.

There is some opportunity now with Danario Alexander out, but Vincent Brown and Malcom Floyd are capable starters and aren't going to be usurped by an "uncertain" rookie.

Chargers rookie WR Keenan Allen saw some first-team snaps alongside veteran wide receivers Malcom Floyd and Eddie Royal.

The San Diego Chargers have lost wide receiver Danario Alexander potentially for the season with a torn right ACL, a source said.

Alexander, who tore his left ACL three times in college at Missouri, has had a history of knee problem.

Alexander emerged as a very good fantasy player last season, catching 37 passes for 658 yards and seven touchdowns in 10 games overall. Over that span he posted #6 WR numbers, and this year we had him ranked as a solid WR3. Vincent Brown and Malcom Floyd will both get a bump in value, but even Brown just recently returned to practice. Also, the Bolts are supposed to simplify things this year, running more with Ryan Mathews, Danny Woodhead and Ronnie Brown, and getting the ball quicker out of QB Philip Rivers' hand. We have Keenan Allen next up on the depth chart followed by Eddie Royal and Robert Meachem, who were both very disappointing last season. At TE, Antonio Gates figures to see a few more targets as well. This is a big blow to Philip Rivers.