Stefan Koubek (born 2 January 1977) is a retired tennis player from Austria. Koubek played left-handed with a double-handed backhand. His idol when growing up was Thomas Muster. Koubek won three titles, two of which came on hardcourts; despite this, he said his favorite surface was clay.
Koubek reached the quarterfinals of the 2002 Australian Open and the 2002 Hamburg Masters, attaining a career-high singles ranking of World No. 20 in March 2000. Koubek tested positive for glucocorticosteroids at the 2004 French Open after receiving an injection for an injured wrist; he was subsequently suspended for three months.
His nickname is Cooley or Stef.
Tennis career
Koubek turned professional in 1994, losing his first match in St Pölten. Between 1994 and 1998, Koubek mostly played in ATP Futures and ATP Challenger Series events.
In 1997 he jumped up 184 positions in the rankings, thanks to good results in Challenger tournaments, reaching finals in Ulm and Alpirsbach. 1998 saw Koubek win his first Challenger event in Alpirsbach; later that same year he lost to Younes El Aynaoui in the final of Maia. Koubek compiled a 33–20 record for the year.
Koubek won his first ATP title in 1999 in Atlanta as a qualifier. He achieved this losing only one set in the whole tournament, overcoming Sébastien Grosjean in the final in straight sets. Koubek reached the fourth round in his French Open debut, losing to Àlex Corretja; to date, this is his best performance at this event. Koubek made the final of Bournemouth, losing to Adrian Voinea, and helped his country Austria back into the World Group of Davis Cup by defeating Sweden 3–2 in a promotion tie. Koubek was second only to Albert Costa in wins on clay during the 1999 season, with 28 match victories.
In 2000 Koubek won his second title in the hardcourts at Delray Beach, defeating Álex Calatrava. He reached the semi-finals at Mexico City, losing to Juan Ignacio Chela. He reached his highest singles rank to date on March 13, 2000, when he became World No. 20. At the 2000 French Open, in his match against Attila Sávolt (the score being 2-1 sets and 5-2 games in favour of his opponent), after having already received three warnings for various transgressions, Koubek was disqualified due to throwing his racket and accidentally hitting a ball boy.
Koubek started off 2002 with his best ever performance at a Grand Slam tournament by making the quarterfinals of the Australian Open. In the first round, Koubek came back from a 0–6 1–6 1–4 15–40 deficit to eventually defeat Cyril Saulnier, 0–6 1–6 7–6 6–4 8–6. In the next round, he again came back from two sets to love down against James Blake, winning in five sets. Koubek then defeated Kristian Pless and Fernando González in the third and fourth roundss, before losing to Jiří Novák in the quarterfinals.
In the remainder of 2002, Koubek's best result was a quarterfinal appearance at the Hamburg Masters, losing to Tommy Robredo. Koubek then finished the year with seven consecutive first-round losses.
Koubek rebounded in 2003 by winning his third career title in Doha. Koubek won the tournament without dropping a set, defeating Jan-Michael Gambill in the final, and briefly holding the top spot in the ATP Champions Race. Koubek's form remained inconsistent, again losing seven consecutive first-round matches after his victory in Doha, before making the semi-finals in Munich, where he lost to Roger Federer. In Davis Cup, Koubek defeated the Belgian brothers Christophe and Olivier Rochus to help return Austria to the World Group.
Koubek made the third round at the 2004 French Open before losing to David Nalbandian. In Thomas Muster's debut as Davis Cup captain, Koubek was instrumental in preserving Austria's status in the World Group, winning both singles matches over Tim Henman and Greg Rusedski.
Koubek tested positive for glucocorticosteroids at the 2004 French Open after receiving an injection for an injured wrist; he was subsequently suspended for three months. The ITF rejected Koubek's appeal of the suspension, but acknowledged that Koubek had not used the drugs to enhance performance. Koubek forfeited his points and prize money from Roland Garros, but his results before Roland Garros were not disqualified.
As a result of injuries and his suspension, Koubek struggled in 2005, and his ranking fell outside the top 100. Koubek spent most of the year playing events on the Challenger circuit. His best results on the tour were a third round in Kitzbühel, losing to Nicolás Massú, and a semifinal in the Helsinki Challenger, where he lost to Björn Rehnquist.