SAN DIEGO -- Keenan Allen isn’t one to back down from the challenge. The fleet-footed receiver out of Cal said he eagerly anticipates facing cornerback Richard Sherman, safety Earl Thomas and the rest of the "Legion of Boom" when the San Diego Chargers travel north for a matchup with the Seattle Seahawks on Friday.

Allen sat out practice on Wednesday, but said he’s healthy and will play against the defending Super Bowl champions in his team’s second preseason game.

Chargers second-year receiver Keenan Allen says he's looking forward to matching up with the Seahawks' secondary. AP Photo/Gregory Bull

“I definitely look forward to competing against ‘the best,’ so to say,” Allen said, smiling. “Yeah, it’s definitely going to be fun. [Cornerbacks Sherman and Byron Maxwell] are pretty long guys with long arms. So it’s definitely going to be a good fight.”

Allen played against Sherman as a freshman at Cal, totaling five receptions for 81 yards in a lopsided loss against Stanford in 2010. Sherman finished with an interception in that game.

But a lot has changed for both since then, with Sherman developing into one of the best cornerbacks in the NFL, and Allen putting together one of the most impressive performances by a rookie receiver in recent memory. Allen finished with 71 receptions for 1,046 yards and eight touchdowns in 2013.

The Seahawks have two of the biggest cornerbacks in the NFL in the 6-foot-3 Sherman and the 6-foot-1 Maxwell, along with the biggest safety in the league in 6-foot-3, 232-pound thumper Kam Chancellor. But the Chargers can counter with size as well. Four of San Diego’s top six receivers on the depth chart are at least 6-foot-2, including starters Allen (6-foot-2, 211 pounds) and Malcom Floyd (6-foot-5, 225 pounds).

Add in athletic tight ends Antonio Gates and Ladarius Green, along with a prolific pass-catcher out of the backfield in Danny Woodhead, and San Diego could give Seattle some problems defensively in the passing game.

Of course, what makes this game unique is both teams will play again in a month when the Seahawks travel to Qualcomm Stadium to face San Diego in the Chargers’ home opener on Sept. 14, so don’t expect either team to show too much schematically.

Chargers receivers coach Fred Graves said execution will be critical in facing one of the most talented defensive backfields in the league. As a group, Graves said his receivers had the fewest drops in the NFL last season with just 13.

“You’re not just going to outrun them and out jump them athletically,” Graves said. “So your technique, your timing and all of that stuff has to be on point. So our guys are ready for them.”

Floyd said he’s not concerned about any verbal sparring against the talkative Sherman.

“I don’t think he does talk mess unless he’s provoked, from what I’ve seen,” Floyd said. “I think he’s a good guy. He’s a smart guy. He went to Stanford, and I think he picks his battles the right way.”