Melbardis and brakeman Daumants Dreiskens won Friday at Canada Olympic Park in a two-run time of one minute 49.60 seconds.
The Latvians moved into a tie atop the overall standings with Francesco Friedrich and Martin Grothkopp of Germany, who were second and just three-hundredths of a second behind the winners.
"First run there were some mistakes, but we focused on the second run," Melbardis said. "It was a great run I think. We need to work on a better push, but it's good and we'll see what happens in Europe."
Olympic silver medallists Beat Hefti and Alex Baumann of Switzerland were third in 1:49.66. Melbardis and Dreiskens were second behind the Germans in last week's season-opener in Lake Placid, N.Y.
Justin Kripps of Kelowna, B.C., and Bryan Barnett of Edmonton were the top Canadians in ninth.
"I had a pretty rough week in training," Kripps said. "Not driving super well, but I put together my two best runs in the race. That's all I could do this week. It's better than last year.
"I was 13th here last year so at least I'm moving in the right direction. I never find the speed on the home track. I have a love-hate relationship with this track."
Calgary's Chris Spring and Lascelles Brown were 12th. Spring was Jesse Lumsden's brakeman when they won bronze last year in Calgary.
Brown and driver Pierre Lueders won Olympic silver in 2006 and Brown was also part of Lyndon Rush's crew that won four-man bronze in 2010.
So Spring, an Australian who earned his Canadian citizenship in 2013, was frustrated with their result Friday.
"I had full intentions of winning a medal here today and it's just a terrible result for me," Spring said. "That second run was terrible by my standards. We're well back from winning a medal here."
Nick Poloniato of Hannon, Ont., and Alexander Kopacz of London, Ont., didn't qualify for the second run.
Olympic women's champion Kaillie Humphries will race the two-woman sled Saturday and then make her World Cup debut as a four-man pilot with an all-male crew.
Kripps will also pilot a Canadian sled. He and crew Barnett, Tim Randall of Burlington, Ont., and Regina's Ben Coakwell were fourth in Lake Placid. Browns will join Kripps's crew Saturday because Randall injured his hamstring racing in Lake Placid.