The men’s game has had defining eras over the years. There have been decades that have been dominated by either two or three players and they have stayed on top. But from time to time, this dominance has been challenged by a youngster that has had a breakthrough season and eventually gone on to be called the no.1 ranked player in the ATP rankings. Thus after Carlos Alcaraz’s victory at the US Open recently that propelled him to top of the table, here is a list of the six youngest players who have been World no.1.

6. Bjorn Borg – 21 years and 78 days (August 23, 1977)

Bjorn Borg achieved the world no.1 ranking shortly after his second Wimbledon title in 1977. He overtook Jimmy Connors who had been the top player for more than 160 weeks. Connors would take back the position after just one week but Borg would eventually be no.1 in the world again and held that spot for a combined total of 109 weeks. The Swedish player retired early just at the age of 26. He had eleven Grand Slams to his name and held on to the Open Era record until Pete Sampras surpassed him.

5. Andy Roddick – 21 years and 65 days (November 3, 2003)

Andy Roddick is the only one on this list to never have the distinction of calling himself the youngest ever world no.1. Regardless, the American’s brief stint on top of the leaderboard came very early on in his career. Roddick had a strong finish to his season winning the 2003 US Open, his only grand slam. He finished the year as the no. 1 but his reign was cut short by Roger Federer in February 2004. The tall heavy server from Austin, TX remains the last American man to have won a major and to have held the no.1 ranking