ASB Classic organisers are withholding a wild card entry to the men’s tennis tournament until the very last minute in an attempt to snare a superstar.

Argentine tennis gun Juan Martin del Potro’s injury withdrawal from the Auckland tournament in January has opened up a hole in the men’s bracket.

Invitations have been dispatched to legends including Roger Federer, Rafael Nadal and Novak Djokovic, as well as other senior players.

Del Potro himself will be replaced by a player from the qualifying rounds, but Classic director Karl Budge said a surprise may still be in order.

The final wild card will be withheld for as long as possible before the men’s qualifying draw on January 6, with organisers already in touch with player agents.

“We always strategically hold a wild card back to try and make last minute offers to other players,” Budge said on Thursday.

“There’s been a lot of phone calls in the last few days, we won’t die wondering.”

One option for the wild card is German tennis stalwart Tommy Haas, who is about to set off on his final year on the ATP circuit.

The 38-year-old, a Classic runner-up in 1999, has already expressed his willingness to travel to New Zealand for the meet.

Budge said Haas would be a crowd favourite, but wanted to first assess his other options.

“He’d like to come and play, he’s asked for a main draw wildcard and a qualifying wild card, so he’s pretty keen,” Budge said.

“He’s been really good to this tournament for a number of years.”

Spanish veteran David Ferrer is the most notable confirmed participant, as well as Marcos Baghdatis and Roberto Bautista Agut.

Americans John Isner, Jack Sock and Steve Johnson are also set to play, as well as Kiwi guns Michael Venus and Artem Sitak.