Dukurs was .17 seconds ahead of defending world champion Tretiakov after Thursday's two runs. Dukurs is the silver medalist from the 2010 and 2014 Olympics.
Dukurs' brother Tomass was in third place, .69 seconds behind the pace.
The final two runs are on Friday.
Christopher Grotheer, German teammate Axel Jungk and Nikita Tregubov of Russia, three leading juniors, were fourth to sixth, respectively.