In fantasy, a sleeper is comprised of equal parts talent and opportunity. Some of fantasy owners’ biggest frustrations happen when young talent wastes away while veterans serve as mediocre starters. Before the season begins, it’s important to assess when and where the opportunities could come, and who’s in line to receive them.

Among those with the most immediate chance to prove himself as a fantasy contributor is Eagles rookie wideout DeSean Jackson. The Eagles’ already-thin group of receivers got even thinner when it was announced that Kevin Curtis could miss nearly half the season with a sports hernia surgery. Fellow rookie Ray Rice and Steve Slaton could also gets early opportunities because of injuries.

Opportunities come in all shapes and sizes and under all different kinds of circumstances. Spot them early, and you’ll be well on your way to a fantasy championship. Spot them late, and you’ll be watching your opponents surge past you in the standings.

Those with developing opportunities:

DeSean Jackson, WR, Philadelphia Eagles
With Kevin Curtis sidelined indefinitely after undergoing sports hernia surgery, the door opens wide for Jackson to crack the Eagles’ starting lineup. He has been their top performing wideout with 12 catches for 122 yards during the preseason, an effort that could propel him into a prominent role in the regular season.

One can’t help but think of Wes Welker when looking at this situation after seeing how a tiny, quick slasher can make an impact moving the chains. The rookie wide receiver jinx certainly applies here, but Jackson is worth a long, long look as a No. 3 or 4 wide receiver in most formats.

Brady Quinn, QB, Cleveland Browns
A mild concussion to Derek Anderson won’t move Quinn into a starting role, but if this is the first of multiple derailments for Anderson, we may have something here. Quinn looked good in relief of Anderson last week against the Giants, completing 7-of-12 passes for 124 yards and a touchdown, and will start on Saturday against the Lions.

No matter how this quarterback situation plays out, it seems to not have a chance to end cleanly. Anderson signed a hefty contract extension in the offseason, but could be pushed out of town a la Drew Brees if the Browns determine Quinn is ready to take the reins. If this concussion proves to be the first in a series of missteps for Anderson, Quinn’s chance could come by season’s end.

Ricky Williams, RB, Miami Dolphins
Williams’ hard work is beginning to pay off with a promotion to the top of Miami’s depth chart. How long that lasts depends greatly on the health of both Williams and 2007 starter Ronnie Brown, who is recovering from an ACL tear and a thumb injury suffered during camp. Williams could conceivably take the job and run with it, but that will take a big effort and/or lingering injuries to Brown in the early part of the season. Even so, Williams makes for a nice value pick at the tail end of drafts.

J.T. O’Sullivan, QB, San Francisco 49ers
O’Sullivan came out of nowhere to jump former No. 1 pick Alex Smith and Shaun Hill on the 49ers depth chart and land the starting quarterback gig. There’s not much offensive firepower in San Fran, but coordinator Mike Martz’s crazy genius can only help O’Sullivan’s season numbers. Isaac Bruce and Arnaz Battle are OK options on the outside and phyiscal freak tight end Vernon Davis could make leaps and bounds in his third year.

O’Sullivan is a fringe backup on standard fantasy rosters, but should remain on owners’ radars as the season begins. If Martz can do the same thing for O’Sullivan as he did for Jon Kitna, Kurt Warner and Marc Bulger, then he has potential to fill in capably during injuries and bye weeks.

Steve Slaton, RB, Houston Texans
Slaton has done well enough for himself to get into prime position for carries. A little on the small side, Slaton can jump in whenever Ahman Green or Chris Brown invariably get injured and make the most of a 12 or 15 carry workload. With his home run potential, those carries could easily turn into touchdowns or big weeks.

Look for Slaton in the last rounds of drafts or on the waiver wire, stash him away at the bottom of your roster, and wait for the potential to come to fruition. If it doesn’t happen in a timely fashion, cut him away and fill another need.

Ray Rice, RB, Baltimore Ravens
Lost in the well-publicized quarterback battle in Baltimore is the fact that Rice is giving injured Willis McGahee all he can handle in a developing running back battle. McGahee’s status for Week 1 has come into question after having arthroscopic surgery on his creaky left knee. An early start would just be icing on the cake for Rice, who can turn the Ravens’ backfield into a Fred Taylor-Maurice Jones-Drew type split.

At this point, Rice seems like a virtual lock for 15 touches per game. Add in McGahee’s health problems, and he’s got a pretty nice situation for fantasy success.

Steve Breaston, WR, Arizona Cardinals
The Cardinals air it out, and Breaston has already established himself as the team’s No. 3 option. If it happens that disgruntled Pro Bowler Anquan Boldin gets traded, as he’s requested, Breaston would be in line for even more looks from quarterbacks Matt Leinart and Kurt Warner. His ability to return kicks and punts adds another element of touchdown potential, which can boost Breaston into the group of No. 4 and 5 wideouts in fantasy.