 Kotelnik made his professional debut on 16 December 2000, scoring a first-round knockout against Peter Feher.On 24 January 2003, Kotelnik won his first regional championship—the vacant WBA Inter-Continental light-welterweight title—following a unanimous decision (UD) over Fabrice Colombel.He defended this title twice before a career first loss on 21 October 2004, a split decision (SD) against Souleymane M'baye.