Denis, the son of Russian hockey coach Genady Tsygurov, was the Buffalo Sabres first selection in the 1993 NHL entry draft, however the pick came in the second round, 38th overall. Regardless, Denis was much touted by the Sabres. They raved about his size - 6'3" and 200 pounds - plus his mobility. He was regarded as more of a defensive defenseman, but had good enough puck skills to start a rush.
Injuries would wreak havoc on the promising career of this Russian defenseman however. In his first year in North American he got into only 32 games total - and only 8 in the NHL. He would make the Sabres straight out of training camp during the lockout shortened 1994-95 season, but only 4 games into the season he found himself traded to the Los Angeles Kings in a huge trade. Denis accompanied Phillippe Boucher and Grant Fuhr to California in exchange for Alexei Zhitnik, Charlie Huddy, Robb Stauber and a draft pick. Denis would finish the season with the Kings, but only got into 21 games thanks to nagging injuries. Denis failed to register a point in that time.
Injuries continued to plague Denis in 1995-96. He only played in 18 games with the Kings (scoring his only NHL goal plus 5 assists) but spent as much time in the minor leagues. By the end of the year he returned to his native Russia.
Denis spent the 1996-97 season in Europe, splitting the season between Russia and the Czech Republic. He attempted a comeback to North American hockey in 1997-98 with 15 games with the Long Beach Ice Dogs of the fledgling International Hockey League. However that venture proved to be unfruitful. He spent the rest of the season in Finland.
Although his NHL days were well behind him, Denis continued to play in Russia until the next century.
Denis played a total of 51 games in the NHL, scoring 1 goal and 5 assists.