McDonald scored nine seconds into the game and in the fifth round of the shootout to send the Blues to a 2-1 victory over the Predators on Wednesday night.
After losing five straight, the Blues have won three in a row, while the Predators have dropped their past two.
In the shootout, none of the skaters scored in the first four rounds.
In the fifth round, McDonald slipped a backhand through the pads of Nashville goaltender Pekka Rinne. Sergei Kostitsyn was Nashville's fifth shooter, but his wrist shot hit the post next to Blues goaltender Jaroslav Halak giving the Blues the win.
"Actually, I talked to (Brad Boyes) on the bench, and he suggested that (move) to me," McDonald said. "That's one that I have had success with in the past, and I try to use something that I am comfortable with."
Beating Rinne in a shootout is a tough task. Rinne has a 14-6 career record in shootouts.
"There will be nights where we get outplayed a little bit and go into a shootout and get the extra point," Nashville coach Barry Trotz said. "This one's tough to take because we really deserved the two points tonight I thought."
McDonald scored nine seconds after the opening faceoff with a wrist shot from the left circle that beat Rinne high to the glove side. The team record for the fastest goal to open a game is 8 seconds set by Greg Paslawski on Oct. 29, 1985, at Washington and matched by Alex Steen against Colorado on March 16, 2010.
"I think it was rolling and we got kind of a bounce," McDonald said. "It's nice to get one early, it's a tough building to play in."
McDonald has 10 points in his past seven games.
St. Louis finished with just 15 shots for the game. Their previous low shot total for the season was 22, set Nov. 7 against the Rangers.
"We overhandled some pucks, we underhandled some pucks, and there was some play that they applied pressure in our own zone that we got ourselves running around a little bit," St. Louis coach Davis Payne said. "In the end, we will take this as two points knowing that we snuck out of here with an extra one or two."
Nashville also found some first-minute fortune when Jerred Smithson drew the Predators even at the 22-second mark of the second period.
Joel Ward carried the puck into the St. Louis zone along the right boards. His shot from the right circle was stopped by Halak, but the rebound landed in the slot, where an unchecked Smithson fired it into the open net for his second goal of the season.
"For the most part, we knew they were a tight-checking team and we weren't going to get a lot of goals," Smithson said. "They have great goaltending, great defense, and they play tight. We had to work for all of our chances."
Halak made 29 saves for St. Louis, ending the Blues' four-game road losing streak.
"On the road we had lost a few games with a high score, so we just need to keep it simple on the road," Halak said. "That was the type of game we were playing at the beginning of the season, so we just need to keep doing the same thing."
The Predators were 0 for 3 on the power play. It was the fifth consecutive game they failed to score with the man advantage and they have just seven power-play goals in 73 attempts this season.
"We definitely played well enough to win," Nashville captain Shea Weber said. "It was just one of those games where we couldn't produce anything offensively. We needed to score goals."
Notes: Wednesday night was Nashville's eighth home game of the season, but three of those eight were against St. Louis, meaning the Blues will not return to Nashville for the remainder of this season. ... Nashville D Ryan Suter returned after missing two games with a lower-body injury. ... With an assist Wednesday, Boyes extended his points-scoring streak to six games. ... St. Louis D Barret Jackman played Wednesday night after missing nine games with a sprained knee.