At the 2000 Summer Olympics in Sydney, Sitnikov competed only in two swimming events. He eclipsed a FINA B-cut of 51.69 (100 m freestyle) from the Kazakhstan Open Championships in Almaty. On the first day of the Games, Sitnikov placed twenty-first for the Kazakhstan team in the 4 × 100 m freestyle relay. Teaming with Sergey Borisenko, Pavel Sidorov, and Andrey Kvassov in heat three, Sitnikov swam a lead-off leg and recorded a split of 52.56, but the Kazakhs settled only for last place in a final time of 3:28.90. Three days later, in the 100 m freestyle, Sitnikov placed fifty-third on the morning prelims. Swimming in heat five, he raced to a fifth seed by 0.15 seconds ahead of Chinese Taipei's Wu Nien-pin in 52.57.