Isner, the 2010 Heineken Open champ, has perhaps made the most of his talent. When the giant with the booming serve and forehand first pitched up in Auckland in 2009 and made a thrilling run through qualifying and on to the quarter-finals in a hail of tiebreaks, he talked wistfully about pushing on into the top 50.
A year later, when he returned and claimed his first ATP title, he was targeting the top 20. Now at 14, he's probably dreaming of re-entering the top 10 (so far he's topped out at nine) and maybe even nicking a Grand Slam. Whatever the case, Auckland is no longer on his calendar.
America's second and third-ranked players, though, will be in town this January. Sam Querrey, a finalist here in 2009 - when he went down to Juan Martin Del Potro - returns with his ranking stable at 22 thanks to a solid 2012.
Tall and powerful at 1.98m and 91kg, Querrey has now banked seven ATP titles and well over $4 million in prize money. His trips to Auckland have been a mixed bag, with 2009's strong run splitting first-round exits in 2008 and 2012.
Despite his consistency on tour, Querrey has never really threatened in the Grand Slams, with a quarter-final appearance in the 2007 US Open his best effort.
Compatriot Mardy Fish is another steady pro. The 31-year-old veteran has reached the quarter-finals in four Grand Slams, but has never progressed beyond that point.
At his peak in 2011, Fish rose to seven in the world, however he was troubled by an irregular heartbeat in 2012 and hasn't played since the US Open. He ended 2012 having failed to win a title for the first time since 2008.