Stunned earlier this week by the news that tailback Michael Bennett could miss the entire season because of a slow-healing foot injury, the Minnesota Vikings were further rocked on Friday, when tight end Byron Chamberlain was suspended by the NFL for four games after a positive test for a banned substance.

	Chamberlain

Two league sources confirmed the suspension and said that the appeal process already had run its course.

Chamberlain tested positive for ephedra, for which the NFL began testing last summer. If his contentions are correct, that he mistakenly ingested the substance while he was taking a dietary supplement, he becomes the latest unwitting victim of the ban. Because of poor or inconsistent labeling, other players claim to have made similar mistakes, and have paid a price for their lack of diligence.

Ephedra is believed to have been the substance responsible for the death of former Vikings offensive lineman Korey Stringer.

The suspension will cost the Vikings the services of Chamberlain for the first four games of the regular season and will cost the eight-year veteran $176,470 in base salary. That is the prorated share of his $750,000 base salary for 2003.

Chamberlain, 31, is permitted to practice with the Vikings in training camp and can even play in the preseason contests. But once the regular season commences, he cannot work out at the team's facility and technically cannot have contact with club officials.

If there are no extenuating circumstances, Chamberlain will be eligible to re-join the team following its Sept. 28 game against San Francisco. His first appearance would then come in an Oct. 5 matchup at Atlanta.

The NFL Players Association sought this offseason to have the four-game suspension for a first-time offender reduced but failed in that initiative.

Minnesota is fortunate, in that it is deep at the tight end spot, but losing Chamberlain is still a setback, since he is the Vikings' best receiver at the position. Jim Kleinsasser and Hunter Goodwin, both proven veterans, are also on the roster. Kleinsasser, designated as the team's "franchise" player this spring, is one of the NFL's best blocking tight ends.

A former Wayne State standout, Chamberlain played the first six years of his career with the Denver Broncos and, while a solid performer, never started a game. He signed with the Vikings as a free agent in 2001, started 14 contests, posted a career-best 54 catches and was named to the Pro Bowl squad.

His numbers fell off in 2002, when he had 34 catches for 389 yards and no touchdowns. In his two seasons in Minnesota, he has 88 receptions for 1,034 yards and three scores. Chamberlain's career resume includes 163 catches for 2,019 yards and six touchdowns. He has appeared in 102 games and started 23 of them.

Len Pasquarelli is a senior writer for ESPN.com.