Sergey Zabolotnov took up swimming in 1971 and made the Soviet national team in 1981. In the middle of the 1980s, Zabolotnov was one of the world top backstroke swimmers, but was often under the shadow of another great Soviet backstroke swimmer, Igor Polyansky. Zabolotnov made his international début at the 1981 European Championships, placing sixth in the 200 backstroke. At the 1982 World Championships he placed seventh in 200 back, but after that medaled in six major meets. He won bronze in the medley relay at the 1988 Olympics, finishing an unfortunate fourth in both backstrokes, and won bronze in the 100 back at the 1986 Worlds. At the European Championships Zabolotnov won the 100 backstroke in 1987, the 200 backstroke in 1983 and 1987 and a the 1989 medley relay. He also won silver in the 100 backstroke in 1989, the 200 backstroke in 1985 and bronze in the 100 back in 1983 and 1985. Zabolotnov missed the 1984 Olympics, and possible medals, due to the Soviet boycott and had to settle for competing at the Friendship Games, a replacement event held by the Soviet Union and other Socialist countries that had boycotted the 1984 Olympics. Zabolotnov won the Friendship Games' 200 backstroke in a world record of 1:58.41. Domestically, Zabolotnov won 11 Soviet titles: 50 backstroke – 1987/89; 100 backstroke – 1980, 1985-87, 1989; 200 backstroke – 1982, 1985, 1987; and the 1984 400 individual medley.
Personal Best: 100 m backstroke – 55.37 (1988); 200 m backstroke – 1:58.41 (1984).