Alex de Minaur has sent Australia’s Davis Cup qualifier with Hungary into a fifth and deciding rubber with a rousing win over Marton Fucsovics.

De Minaur came out on top in the marquee match-up between the two nations’ No.1s with an electrifying 7-6 (7-4) 6-4 victory that locked the Sydney tie up at 2-2.

“The job’s not done,” de Minaur said before Thanasi Kokkinakis and Zsombor Piros took to the court to battle it out in a winner-takes-all showdown at Ken Rosewall Arena.

The triumphant team will progress to September’s group stages of the competition.

Hungary had taken a shock 2-1 lead with a stunning doubles win in Saturday’s first match.

Hungarian captain Zoltan Nagy’s late team change paid huge dividends when Mate Valkusz and Fabian Marozsan upset John Peers and Davis Cup debutant Luke Saville 6-4 6-4.

After initially naming Fucsovics to partner Marozsan at Thursday’s draw, Nagy opted to rest his singles spearhead for the first reverse singles match against de Minaur.

The visiting skipper only made the announcement half an hour before the doubles, but Valkusz — ranked 1312th in doubles and the world No.439 singles player — proved an unexpected success.

“It’s crazy,” Valkusz said after winning his first-ever Davis Cup match.

Peers, a former Australian Open doubles champion and a winner of the Olympic bronze medal in mixed last year with Ash Barty, cut a forlorn figure after double-faulting on match point.

He also dropped serve three times in the first set as the home fans watched on almost in disbelief.

“I don’t think we played the best match we could have but I feel like those guys played a really good level and didn’t really let us settle,” Peers said.

The defeat left de Minaur and Kokkinakis needing to win both Saturday’s reverse singles to rescue Australia.

Not since Hewitt and Sam Groth posted last-day wins against Kazakhstan in the 2015 quarter-finals in Darwin has Australia overturned a 2-1 deficit in the famous teams’ event.

Fucsovics was rested after digging deep to beat Kokkinakis 7-6 (7-4) 1-6 6-3 in Friday night’s second singles rubber to level the tie at 1-1 after de Minaur gave Australia the early initiative with a 7-5 6-2 victory over Piros.

But despite Hungary easing Fucsovics’ workload, de Minaur wore the world No.35 down in the sapping humidity under the arena’s closed roof.

De Minaur rallied from 3-0 and 4-2 down in the crucial first-set tiebreaker and then withstood a fierce second-set fightback from Fuscovics to finally seal the must win on his fourth match point.

“This Aussie team is going to do everything to leave it all out there on the court,” de Minaur said.

“We’ve got immense pride, immense passion and one thing you can count on from the Aussie Davis Cup team is we’re never going to give up.”