Haas was recently named ATP comeback player of the year for his remarkable climb up the world rankings and Kohlschreiber has had his best season yet.
After making the semifinals in Auckland, Kohlschreiber went on to his fourth tour title in Munich, made the quarter-finals at Wimbledon and reached a career high ranking of 16.
Former world No7 Mardy Fish, who has been struggling with a heart complaint, has had to withdraw from the tournament for health reasons but the ranking cutoff for direct entries will still be 61.
Heineken Open tournament director Karl Budge is excited about the number of players coming to Auckland who are in some of the best form of their careers, including defending champion David Ferrer.
"Tommy is showing, like Ferrer and [Roger] Federer, that age is no barrier," Budge said. "To get to 21 in the world is a great feat. And Kohlschreiber has had his best year on tour, reaching number 16 in the world. He comes back for his ninth Heineken Open playing his best tennis yet.
"I don't need to say much more about Ferrer beyond stating that he won more titles than any other player on tour this year with a career-best seven."
Budge pointed out that, when you add Melzer to the mix, you might start to think the older brigade will have a mortgage on next year's title.
"However, I suspect that the world's top newcomer Martin Klizan and the Paris Masters giant killer Jerzy Janowicz will add plenty of young fire to the contest."
Haas, who was a finalist in Auckland in 1999 and has since gone on to win 13 titles and make four grand slam semifinals, will be the tournament's third seed.
World No5 Ferrer will be top seed, followed by Kohlschreiber (20), Haas (21), Querrey (22), Poland's Janowicz (26), Austria's Melzer (29) and ATP newcomer of the year Klizan of Slovakia (30).
Also announced yesterday was Brazil's Thomaz Bellucci who sits just outside the top 30 at 33 in the world. He will be playing in Auckland for the fifth time.
