Once regarded as one of the most promising players in Europe, But signed in 1994, at not yet 17, with German side Borussia Dortmund, from local FC Chernomorets Novorossiysk, but spent his first years with the juniors.
On 21 August 1996, he finally made his first team debut, appearing in ten minutes of a 4–0 home league win against Fortuna Düsseldorf.
But finished his first season with 11 matches and one goal,[1] and added two games (three minutes total) in the club's victorious UEFA Champions League campaign, becoming the second Russian player to win the competition after Igor Dobrovolski.
In late October 2000, But left Borussia after falling out with coach Matthias Sammer, and joined SC Freiburg where he stayed for the next three seasons, appearing regularly (but also being relegated at the end of the 2001–02 campaign).
In June 2009, But signed with Greece's OFI Crete as a free agent, but retired from football after one unassuming season.