By Ridge Mahoney

An officiating nuance came into play last weekend in the D.C. United-Chivas USA match when a Chivas USA goal was disallowed because of an offside that had preceded the shot by nearly 30 seconds.

Defender Tim Regan played a long ball down the left wing to Francisco Mendoza, whose pass triggered a sequence during which Francisco Palencia hit the post and Juan Pablo Garcia eventually scored. Referee Marcel Yonan hadn't checked to see if the referee's assistant had raised the flag for offside when Regan played the ball to Mendoza, but did so prior to Garcia's shot, and blew his whistle well before the ball hit the net.

The flag stayed up as play continued because Yonan did not acknowledge he had seen the signal and because the offside player touched the ball.

If the referee acknowledges the signal and waves play to continue, the referee's assistant lowers the flag. The assistant would also lower the flag in case of a passive offside if a different player touched the ball, but since the offside player did touch it, the official is obligated to keep the flag up until the referee acknowledges it. The assistant also holds his position on the touchline.

Yonan erred in not glancing at his assistant when the ball was played wide, yet while disallowing the goal made a gesture that indicated what had happened.

This is where a sideline reporter can be useful by checking with the fourth official, who can speak to the referee via their communications system, get an explanation, and relay the information to the reporter.

BARCA BUCKS. Barcelona will visit the U.S. for three games in August and according to a source will be paid $750,000 per match.

According to the official release, the club will bring all of its first-team players: Lionel Messi, Ronaldinho, Samuel Eto'o, etc. Such arrangements are always subject to change, of course, and in many cases the appearance fee drops if a few stars opt out.

Only one opponent has been confirmed. Barcelona will conclude its tour Aug. 12 against Red Bull New York at the Meadowlands. Foes for games in Los Angeles Aug. 6 and Houston Aug. 9 will be Mexican clubs.

CD Guadalajara, not the MLS version, is the obvious Los Angeles opponent, except for a possible conflict if it reaches the two-leg final of the Copa Liberatadores, which is scheduled for early August.

Another snag may prevent rival Club America, which for more than a year contemplated an MLS investment in Houston, from filling the Texas date. Media conglomerate Televisa, which operates Club America, is reportedly insisting it control TV rights to the match. Barcelona and tour promoter SUM have their own ideas.

Club America is planning a U.S. tour this summer as well and obviously a Barcelona matchup would be the glamour game, so more likely than not some compromise can be worked out. If so, Reliant Stadium (capacity: 69,000) might not be big enough.