Helping keep Tkachuk and the United States at bay, Kristers Gudlevskis amassed 45 saves for Latvia.
After recording five points (3G, 2A) in 19 games with the Panthers this season, Vilmanis has brought that strong play from his NHL debut to the World Championship.
Producing at better than a point-per-game clip, the 22-year-old forward is tied for first on Latvia with six points (2G, 4A) at the tournament.
With the win, Latvia jumped ahead of the United States in the standings and now sits fourth in Group A.
USA, which trails Latvia by one point, has two games left in the group stage against Hungary and Austria.
Latvia, meanwhile, has two games remaining against Great Britain and Hungary.
Only the top four teams from Groups A and B will advance to the quarterfinals of the tournament.
For more information and a full schedule of the World Championship, click HERE.