A month ago, Rick Bragnalo was a nonproducing fourth-string center with nightmares that centerd around a return to the International League bus belt.

Yesterday, the pocket-sized 155-pounder, converted to left wing because of injuries, produced the third-period goal that lifted the Washington Capitals to a 2-1 victory over the St. Louis Blues at Capital Centre.

It was Bragnalo's third goal in five games - he went 16 without a score earlier this season. Since the Capitals have connected only eight times in that stretch, it's easy to see he has become a pretty big man.

The pass that set up the game winner came from Bill Riley, only two days removed from the bus brigade. Riley was en route to Saginaw, Mich., with the Dayton Gems the other day when he was told to prepare for a plane trip, to join the Capitals in Toronto.

Riley outfought the Blues' Jerry Butler for the puck on St. Louis ice, fired a perfect pass to Bragnalo in the slot and saw Bragnalo's 30-foot drive sail over the left shoulder of goalie Ed Staniowski, whose view was screened by Gerry Meehan.

More than 17 minutes remained, but ther was no further scoring, mostly because Washington goalie Ron Low as a hot item in a cold building.

Low blocked nine shots in the third period, including a great stop on Larry Patey, who broke behind the Capitals' defense with 50 seconds left.

Low had played a tough game in Toronto Saturday night, where the Capitals lost, 3-1, but he claimed he wasn't tired. "I slept good. The more I play, the sharper I feel," he said.

St. Louis, which beat Minnesota, 3-1, Saturday night, used Staniowski for the first time since Dec. 15, resting No. 1 man Eddie Johnston. But Washington coach Tom McVie never gave a thought to such a move.

"I'm not in favor of a two-goalie system," McVie said. "It gives a coach too many decisions to make."

McVie made another change, however. He started a line of Mike Marson, Guy Charron and Riley because he "wanted some hitting early to set the tempo for the game."

He got plenty of hitting. There was so much hitting that the Capitals didn't get around to taking a shot on goal until the nine-minute mark, when Staniowski defelcted a testing backhander by Bragnalo.

The hitting got out of hand after Riley stole the puck from St. Louis defenseman Bob Bassoff, who frequently mishandles the puck and responds with fists and stick. This time it was the stick, as he slashed at Riley, who responded with a cross check.

Riley dropped his gloves inviting fisticuffs, but Gassoff did not even release his stick. Marson, previously involved in a dispute with the belligerent Blue, went after him again and St. Louis' Ted Irvine pulled Marson down.

The Capitals' Bryan Watson dove at Irvine and soon there was an 11-man battle in frontof the St. Louis net, with Staniowski privileged to participate without leaving his crease.

When it ended, Washington captain Yvon Labre was sitting on Rod Seiling and Watson had Butler icebound. Referee Bryan Lewis issued nothing but minor penalties and the teams returned to hockey.

The Capitals did, anyway. The Blues' Garry Unger was observed shoving the butt end of his stick at Marson, then Gassoff speared Patey. Everybody knows crime doesn't pay, though, and the Blues eventually paid with the end of their five-game unbeaten streak.

There was a horrible moment of doubt, however. St Louis broke a scoreless tie at 8:38 of the second period when Rick Green dropped his stick, the puck became entangled with his stick and skates, and after an incredible waltz toward the Caps' net it popped to Pierre Plante, who beat Low from directly in front.

"I've never seen anything like that," said the embarrassed Green. "One of their guys was shooting it in and I was going to use my left hand to knock it down.

"It was closer to my right, and when I switched, I dropped the stick. The puck was trapped under my stick and I couldn't get out of the way. I should have just kicked the whole works."

Hartland Monahan was there, along with Plante, but Monahan said, "It got in between his (Green's) skates. We were starting to get in too close and I tried to get it, but the other guy went in at the same time and hit it in."

Washington, which had never before earned a point against the Blues, pulled even five minutes later when Monahan dropped a pass to Gordie Lane, who connected with a 40-footer. St. Louis defenseman Bruce Affleck helped out by screening his own goalie lie.

Lane's ex-teammates who played for McVie at Dayton weren't to be outdone. Riley and Bragnalo joined the fun, sending the Capitals' five-game losing streak into discard.

"For a while I wasn't playing at all," Bragnalo said, "and when I did play I couldn't do anything. I couldn't pass the puck 10 feet.

"I've got a little different attitude now, though. You've got to try not to feel sorry for yourself, to do the best you can."

Riley, whose best fist forward is his ticket to steady employment, isn't about to be intimidated be sassy Gassoffs.

"I have to play the same way that got me here," Riley said. "I like the rough stuff. If I run into somebody or somebody runs into me, it gets me in the game more."

The victory was the Capitals' 11th of the season, matching their total of last season. They won only eight in 1974-75 . . . The NHL game of the week telecast on Monday nights has been picked up by WBFF-TV-45. Tonight's premiere matches Philadelphia and Montreal . . . Bob Sirols, who suffered a broken left thumb Dec. 7, is expected to rejoin the Capitals for Tuesday's home game against Detroit.