Alexander Zverev became world number one at the start of this week following Jannik Sinner's absence due to knee injury. In his first match in the top ranking, Zverev fell to Lorenzo Musetti 7-6(5), 6-2 at the Paris Masters. This defeat makes Zverev the fifth ATP player in history to lose his opening match after reaching number one.
John McEnroe started this unwanted list in March 1980, losing to Jose Luis Clerc in a Davis Cup tie despite holding the top ranking. Thomas Muster fell to Sandon Stolle at the Dubai Tennis Championships in February 1996, while Lleyton Hewitt lost to Nicolas Escude in Davis Cup action in November 2001. Carlos Alcaraz, who became the youngest world number one ever in September 2022, was defeated by Felix Auger-Aliassime in Davis Cup play.
Zverev's distinction lies in being the only player on this list to lose his first match as number one in straight sets. Pat Rafter holds the record for the shortest reign at number one with just one week, though he never competed during that period.
