Rising stars Nick Kyrgios and Thanasi Kokkinakis are in danger of getting the boot for Sunday’s crunch Davis Cup showdown with Kazakhstan in Darwin.

Lleyton Hewitt and Sam Groth kept Australia’s title hopes alive with a 6-4 7-6 (7-4) 6-2 win over Andrey Golubev and Aleksandr Nedovyesov in Saturday’s doubles clash.

Despite the win, Australia still trail 2-1 in the tie, meaning they need to win both of Sunday’s singles matches if they are to progress through to the semi-finals.

Kyrgios and Kokkinakis were initially pencilled in to take part in those matches.

But both their positions are looking tenuous after they slumped to disappointing losses on day one.

Kokkinakis appears to be the most vulnerable after struggling to handle the grass-court conditions in his 6-4 6-3 6-3 defeat to Mikhail Kukushkin.

And an emotionally-drained Kyrgios could also be forced to make way after his shock four-sets loss to world No.115 Aleksandr Nedovyesov.

Davis Cup captain Wally Masur has up until an hour before each match on Sunday to decide his line-up.

Masur said he would consult with Davis Cup legend Tony Roche and coach Josh Eagle before making a final decision.

“Obviously form and confidence are important,” Masur said.

“I was really impressed with these two guys (Hewitt and Groth) today.

“They had great clarity; they knew exactly what they had to do with our backs against the wall.

“It was a really good team effort, so I do have decisions to make based on the results over the weekend, and hopefully we get it right.”

Kyrgios has been in the thick of the headlines for much of the past month, and the spotlight appears to have taken a mental toll.

“That’s no different to being physically exhausted after a big month or a big match,” Masur said.

“It takes its toll.

“I kind of feel sorry for Nick in a way because it was almost a little bit of hysteria about some of the stuff that went on at Wimbledon.

“The press cycle just kind of went into overdrive.”

Hewitt has already established himself as Australia’s greatest Davis Cup player, and the 34-year-old declared he would be ready to fire once again if called upon for a singles match on Sunday.

Groth’s powerful serve-and-volley game makes him an attractive prospect as well.

Hewitt gave Groth a big hug once they wrapped up their doubles match in 2hr 25min.

And their energetic chest bump during the second set was another big highlight.

“It wasn’t something we planned, it just sort of happened,” Hewitt said with a smile.

“I love playing with Grothy, he has a lot of emotion out there.”

Kazakhstan captain Dias Doskarayev said his team remained positive despite their doubles loss.

“There is no panic,” he said.