Redskin fullback John Riggins, who sprained his right ankle against the New York Giants, is expected to play in Sunday's game against the St. Louis Cardinals at RFK Stadium.

Riggins was injured in the fourth quarter of the Redskins' 16-3 overtime victory over the Giants Sunday and left the locker room on crutches, with a cast on his foot.

He probably will not be able to practice for a few days.

Team physician Stanford Lavine removed the cast yesterday and indicated Riggins' condition would be evaluated on a "day-to-day" basis, but that the sprain was not severe.

Riggins will undergo the usual rehabilitation - alternated ice and hot whirlpool, ultrasound and exercise. A team spokesman said Lavine seemed optimistic about Riggins for Sunday. Lavine was not available for comment.

Center Ted Fritsch the other major casualty from the Giants game, remained in Sibley Hospital another night, having had three ribs broken while blocking on a punt return during the overtime.

Fritsch wobbled onto the field after the injury to make the snap on Mark Moseley' game-winning 45-yard field goal. But after the game he had difficulty breathing and was taken up to the hospital in an ambulance.

Redskin Coach Jack Pardee said he thought Fritsch would be available to do what he does best - snap the football on punts and placements - but the he probably would not be able to play on other special units.

"The early indication is that with some padding he'd be able to snap," Pardee said, "but we'd take him off the rest of the teams. Those are very painful injuries: you don't even want to sneeze."

Pardee also strongly hinted that he would make another change in his offensive line. Second-year man Jim Harlan apparently has recovered sufficiently from a sprained left knee to move in at right tackle, the position manned by George Starke until his season-ending knee injury against the 49ers.

Harlan's replacement the last two games has been Jeff Williams, put on the roster only last Monday after rejoining the team 12 days ago. Williams was victimized frequently by Giant defensive and George Martin who was credited with four of the Giants' five sacks of quarterback Joe Theismann.

"What Jeff did yesterday doesn't mean we're down on him," Pardee said. "A guy who's been in your camp only two or three days is going to have some trouble. It was just a matter of some technique, and that's something you need practice time on, Jeff hasn't had that time.

"Jim (Harlan) through the year had been playing every week until he was injured. He's more familiar with what we've been doing. Jim should be more prepared to go physically this week."

Despite his injury problems, Pardee seemed mostly relieved yesterday, particularly because of his team's play in the final 2 1/2 minutes of regulation and the overtime session against the Giants.

"If we play that way, we can play competitively with anyone," he said. "Otherwise, it's a struggle. I just hope it's a sign that we'll keep playing that way."

Pardee also admitted that 11 victories may not be enough to assure winning the NFC East Division title, particularly with Dallas apparently rolling again and only a game behind.

"Like everybody anticipated, it's going to go down to the wire," he said. "Our remaining schedule is rough, and so is the Dallas schedule. There are no shoo-ins right now for any of the spots."

The Redskin next take on a Cardinal team that has won three straight, follow with a Thanksgiving Day shootout against the Cowboys in Dallas, a home game against Miami, go to Atlanta and play the Bears here in the season finale.

The Cowboys have three straight home games left against New Orleans, Washington and New England, followed by games at Philadelphia and in New York against the Jets.

And a half-dozen over NFC teams have legitimate shots at playoff berths, either by division title or the wild card route.

Pardee said he has been impressed with the play of the Cardinals the last three weeks, especially on defense. St Louis has given up only 30 points and three touchdowns in beating the Eagles, Giants and 49ers.

"They're using a three man line almost exclusively, and they look like they're going out there and having fun," he said. "They've gotten their offensive line back together and all their people seem to be coming around."

The same could be said on Redskin quarterback Theismann, who set a personal pro career mark with 22 completions in 35 passes for 270 yards and no interceptions against the Giants.

Pardee was asked if the thought Theismann's benching against the 49ers and Colts was the best thing that could have happened to his quarterback.

"That wasn't the purpose of it," Pardee said. "At that time, we were having other problems. Jean Fugett's knee was bad. Mike Thomas was out. Joe was taking too much of the burden, trying to make something happen that wasn't there.

"Against the Giants, he went back into the old routine, hitting the backs out of the backfield, doing the things that the good quarterbacks do. It (the benching) made an impression on him that a quarterback can't do everything himself. But we didn't make the change as a put-down to Joe."

The Redskins are 5-0 at home and have won 45 of their last 55 games at RFK. Their 13 penalties for 106 yards against New York was a season high as were 219 net passing yards . . .

Redskins have a five-game winning streak over the Cardinals . . . Redskin special teams continue to lead the NFL in punt return defense, allowing only 3.2 yards a kick, a figure that helps Mike Bragg remain the league's leading net punter, with a 37.4 yard average per kick . . . Moseley's three field goals and an extra point moved him into second place in the NFC scoring race with 69 points, trailing the Rams' rookie kicker, Frank Corral, by one point.