The duo have been announced this morning while another American, former finalist Sam Querrey has also confirmed to NZME at the Shanghai Masters, he's returning to the Classic.
The trio add to the already announced defending champion Roberto Bautista Agut (ranked 19) for a field that will probably lack the star power of the ASB women's Classic, it's headline act is Serena Williams, but will have strong depth.
There are now four players confirmed in the top 30 and while there will be more between 20 and 30, it's unlikely there will be any others ranked inside the top 20.
Ferrer has won the Auckland title four times and will seek to break the record he shares with Australian Roy Emerson, while Isner is a twice former champion at the ASB Tennis Arena.
The Spaniard has been an almost ever present in Auckland since his first appearance in 2003 and it's his loyalty to the tournament which is something to be admired. While the 34 year old is in the twilight of his career and no longer in the top 10 (ranked 15) he is still one of the most competitive players on tour.
"I am always very happy to play in Auckland. It always has very strong competition and is a nice crowd to play in front of. I feel at home there. I have had a lot of success in Auckland and I hope that I can win one more event." Ferrer said.
Isner was ranked just outside the top 10 when he visited Auckland a year ago and is currently ranked 26. The 31 year old has won 10 ATP titles including Auckland in 2010 and 2013.
"It's always been a special place, and it's where I won my first tournament there .For me it's the best way to start off the year and is great preparation for the Australian Open. The tournament is amazing, the city is amazing and it keeps getting better." Isner said.
His form has been erratic in 2016 but he believes he can return to near the top next year.
His best results this year have been reaching the last 16 at both the Australian and French Opens and finishing runner up to Nick Kyrgios in Atlanta.
"It's been a difficult year, I've lost a lot of close matches, but the most important thing is I feel fit and healthy and will be excited to go in 2017."
The ASB Classic has become a regular stop for American players en route to the Australian Open and Isner expects a number of his compatriots to enter.
"Us American's prefer Auckland, that's why you see us keep going there to play and we all see it as perfect preparation for the Australian Open."
This year's runner up Jack Sock (ranked 25) and fellow American Steve Johnson (24) are expected to be unveiled in the coming weeks and with veteran Querrey at 29 in the rankings, there could be four American players among the seeds in Auckland.
Rising star 18 year old Taylor Fritz is another target, who could possibly be swayed by a swag of his compatriots playing in Auckland.
Querrey's year has been highlighted by a stunning second round victory over defending champion, world number one Novak Djokovic at Wimbledon.
Tournament director Karl Budge is still hopeful all eight seeds will be ranked inside the top 30 which is an outstanding result for a tournament like Auckland that is finding it increasingly difficult to convince top 20 players to play the week before the Australian Open.
Budge put offers out to the likes of Dominic Thiem, Tomas Berdych, Marin Cilic and former champ Juan Martin del Potro and while in del Potro's case, he hasn't heard back, the others have said no.
Frenchman Jo Wilfried Tsonga, the star attraction this year, and been swayed by a big money offer in the Middle East, and as the rankings stand, as many as 16 of the top 20 simply won't play an ATP tournament, either Sydney or Auckland, the week before the Australian Open.
Budge would love to see the calendar change to allow the men's and women's ASB Classic's to cross over with a men's final staged potentially midweek to allow players more time in Melbourne to prepare for the year's first Grand Slam. It's a radical suggestion, but has merit. Whether the powers that be who run tennis listen, is anyone's guess.
But at the start of the year when players need matches ahead of the year's first Grand Slam, it seems crazy so many chose not to play the events which are part of their Tour.
