The Washington Diplomats yesterday placed striker Paul Cannell on the 21-day injured list and said Johan Cruyff stands only a 50-50 chance of playing Saturday night when the struggling Dips host Minnesota in RFK Stadium.

Cruyff did not work out with the team yesterday, instead spending the day at the Sports Medicine Center in Chevy Chase trying to strengthen a pulled groin muscle he suffered Sunday.

Cannell, too, is said to be suffering from a groin injury and possibly will not play again this season. The Diplomats have been a relatively healthy bunch all season but now are beset with all kinds of injuries. Coach Ken Furphy will have a difficult time replacing the three North Americans who are injured.

David Bradford, the team's most consistent player all season, missed yesterday's practice because of the flu and a bad throat irritation. He will be listed as questionable for the Minnesota game.

Ivan Belfiore, a starting defenseman and a North American, is also out with a groin pull. A team spokesman said yesterday that Belfiore couldn't lift his right leg.

Benny Dargle, another starting defenseman and North American, is questionable with a pulled stomach muscle. Trevor Franklin, also a North American defender, is suffering from nect spasms and is in traction. He is on medication and is listed as doubtful.

The Dips are struggling to make the playoffs. A loss to Minnesota on Saturday could seriously damage their chances for postseason play. The only apparent bright spot is the return of defenseman Eddie Colquhoun, the 35-year-old player-assistant coach, who came off the injured list yesterday after suffering from gout.

Colquhoun probable will start Saturday. Furphy is hoping he will lend stability to a Washington defense that has given up easy goals in the last four or five games.

With Colquhoun back on the roster, the Dips had 14 foreign players, one over the NASL limit. So General Manager Duncan Hill was faced with the decision of cutting a foreign player or putting somebody on the disabled list. Cannell, who has scored only one goal this season in limited playing time, was a logical candidate for the injured list.