Russia's Daniil Medvedev has replaced Novak Djokovic at the top of the world rankings, two weeks before a Wimbledon at which he will not be allowed to play.
Wimbledon has been stripped of its ranking points over its decision to ban Russian and Belarusian players over the Russian invasion of Ukraine.
However, that decision means Medvedev, 26, is likely to increase his lead over Djokovic at the end of the tournament because the Serb is defending champion so has more ranking points to lose.
Djokovic has dropped to world number three, with the injured Alexander Zverev rising to second.
It is the first time since November 2003 that none of Djokovic, Rafael Nadal, Roger Federer or Andy Murray have appeared in the top two rankings spots.
Wimbledon excluded Russian and Belarusian players from participating this year because of Russia's invasion of Ukraine - leading the governing bodies of the men's and women's games, the ATP and WTA, to remove ranking points from the Slam.
Djokovic, a six-time Wimbledon champion, will lose the 2,000 ranking points he secured when he lifted the men's title at SW19 last year.
Medvedev became the first player other than Djokovic, Nadal, Federer or Murray to top the men's rankings since American Andy Roddick 18 years ago when he briefly replaced Djokovic as number one in February.
