Melbourne, Oct 13 (IANS): Australia batsman David Warner has 15 days for his still broken left thumb to heal if he wants to be selected for the first cricket Test against New Zealand, coach Darren Lehmann said on Tuesday.

Lehmann said the injured opener has to play the opening round of the domestic Sheffield Shield tournament in order to be picked for the Test at Brisbane, which starts on November 5, reported cricket.com.au on Tuesday.

X-rays on Friday revealed Warner's thumb to be still broken, four weeks after he was struck by a delivery from England's Steve Finn.

Warner will have another x-ray this coming Friday and is hoping to test out the injured digit at the nets for the first time next Monday, nine days before New South Wales' Shield match against South Australia gets underway on October 28.

Both Lehmann and Warner are confident the vice-captain will be fit for the day-night game at the Adelaide Oval, with the coach adding the match was an essential part of Warner's preparation for the New Zealand series.

"I'm pretty sure he'd have to play," Lehmann said.

"If he's not going to play that he's probably not going to be fit enough (for the first Test). Again, we'll cross that bridge when we come to it but all signs are he's going to play."

Lehmann said playing just the one Shield match would be enough for Warner to prove he's ready for the first Test. "For him, yeah. He's played a lot of cricket anyway," Lehmann said.

"You'd love him to have a bit more time but we're not too worried about it, especially with the way he plays."

Selectors will decide on Australia's squad for the first Test on October 29.