The real de Minaur is shining at Davis Cup

Will the real Alex de Minaur please stand up?

Not the excellent battler who so often falls just that bit short against the very best - but the super-charged bantamweight who seems to be infused with extraordinary resolve and a heavyweight's punch whenever he dons his country's green and gold.

Yes, even Australia's No.1 tennis man accepts that he appears to become a different athlete when he's in the Davis Cup zone.

After his victory over Dutch No.1 Botic van de Zandschulp in Malaga - his ninth win in his last 10 Davis Cup singles that thrust Australia into Friday's semi-finals - he was asked how he'd describe this superman transformation.

"I reckon probably what I need to take it to the next level on the ATP Tour is to bring this Alex more often," he smiled.

"But there is something special about representing your country and playing for Australia and being part of this team.

"This has always been a dream of mine, and I will always do everything in my power to try and deliver for my country, my teammates, and my captain.

"It's pride, it's passion, and it's a whole lotta heart."

De Minaur is certainly going to need more of these magic ingredients when he faces an old Croatian foe, Marin Cilic, in Friday's (Saturday AEDT) semi-final.

Former US Open champ Cilic, still powering on at 34, was buoyant after an epic three-set win of his own against Pablo Carreno Busta that knocked out the hosts Spain in Wednesday's quarter-final.

He's also armed with the memory of an epic five-set win over de Minaur at the 2018 edition of Flushing Meadows.

And even more significantly, he also held off a fighting rearguard action from the Sydneysider to win a fabulous duel at last year's Davis Cup which took the Croats to a group tie victory.

That performance, after de Minaur had largely been outgunned, had his team captain Lleyton Hewitt hailing it, even in defeat, as one of his key lieutenant's finest performances.

De Minaur hasn't lost a Davis Cup singles since, going unbeaten in six matchs, but he'll have to go one better against Cilic this year if he's to guide Australia to their first final since 2003, when they last lifted the title against Spain in Melbourne.

For Croatia will again be favourites for the tie, fielding perhaps the most powerful team on view in Malaga with Cilic ranked 17 in the world, a refreshed Borna Coric back up to No.26 and their Olympic champion doubles team of Mate Pavic and Nikola Mektic.

So it's going to take another monumental effort from Jordan Thompson, a three-hour, come-from-behind winner against Tallon Griekspoor on Tuesday, against Coric, who's returning to near his best after shoulder surgery.

And it could all come down to a potential doubles classic between Australia's own formidable combination of Matt Ebden and Max Purcell, the Wimbledon champions, and Mektic and Pavic, who took the title at the All England Club the year before.