The Chargers' second-year wide receiver is seeing the field more with Parker's neck ailing and Keenan McCardell being in and out of the lineup with his bum calf.
Jackson has proven to be the NFL's highest-scoring team's best deep threat of late, and the present situation shows him getting plenty of action on Sunday in Seattle when the Chargers go for their eighth straight win.
"He's come a long way,'' Philip Rivers said of Jackson, a second-round pick. "But I think we all knew what he could do.''
Others have found out. Especially the last two weeks,when he has come through with big-time catches at critical junctures in the games.
His 46-yard snag in the fourth-quarter Sunday set up a Nate Kaeding field goal. It also brought some rare life to a passing game, which was terrible.
Against Denver on the previous Sunday, Jackson caught a career-long, 55-yard catch. That, too, led to three points.
Overall, Jackson has 19 catches for 328 yards and three touchdowns.
But just as important is Jackson's ability to stretch the field. Defenses love to gather near the line of scrimmage to counter LaDainian Tomlinson and Antonio Gates. By Jackson wiggling deep for an occasional long pass, it helps the two Pro Bowlers.
"He's made very, very steady progress throughout the season,'' coach Marty Schottenheimer said of Jackson. "He has more confidence in himself, we have more confidence in him and the quarterback has more confidence in him. As a result, he's getting more opportunities.
Seattle running back Shaun Alexander wouldn't mind getting less work during the exhibition season. But he also understands why he gets more preseason work than Chargers counterpart LaDainian Tomlinson.
"Every player is a little bit different," Alexander said. "He and I are more similar than anyone I have ever been around.
"Both of us don't like to do too much (in preseason) because we like to have an edge. A lot of our game is just reaction, so we need to do a little bit to not be rusty, but at the same time, you don't want to do too much because then you get caught up in just being a robot and you almost cover your own talent."
Alexander carried 22 times for 76 yards during the preseason. Tomlinson had zero carries.
"I probably still do too much, but that is probably because of how coach (Mike) Holmgren is about our system," Alexander said. "Our offensive system is just different. Being in the West Coast, it is so much timing. Theirs isn't."
This is the first season Alexander has had to deal with significant injuries. He suffered a broken bone in his foot as early as the season opener. The injury eventually forced him to miss six games. Tomlinson has appeared in 93 of 94 possible regular-season games since entering the league with the Chargers in 2001.
Alexander set the NFL single-season record for touchdowns last season. Tomlinson broke the record this season. Their showdown Sunday has lost a lot of its edge because Alexander and the Seahawks are struggling. But it's still a game both are anticipating.
"I was motivated about this game when the schedule came out," Alexander said. "LaDainian is a good friend of mine and he is a great talent, a great person.
"Our careers are so similar in so many ways. People like that, you get excited to play against. Of course, we won't be on the field at the same time, but it is cool to play against somebody like that."