Thompson has just got back into action after an injury-ravaged year but Hewitt has had no hesitation plunging the ever reliable 31-year-old fighter into the team which must win the two-day tie at the Ken Rosewall Arena on September 13-14 if they're to qualify among the eight teams for the finals in Bologna in November.
Alex de Minaur will, as ever, lead the lineup alongside Alexei Popyrin, with Hewitt potentially having the luxury for the first time of being able to field two top-20 players in the four singles ties.
He'll also have Thompson, ranked 50 in the world, as a singles back-up while Olympic champion Matt Ebden has also been selected to join him in a formidable doubles partnership. The pair have been gaining useful practice, playing alongside each other at this week's Cincinnati Open.
With only four players listed so far, Hewitt could also yet include another name to his team list should there be any injury concerns over the busy and demanding US Open spell.
In contrast to the Australians being able to field three top-50 singles players, the Belgians have only one top-100 player, world No.54 Zizou Bergs, in their squad.
Raphael Collignon (No.107) and Alexander Blockx (119) will be battling for the other singles berth, while Joran Vliegen and Sander Gille are both top-100 doubles players.
Thompson made his return to action last week in Cincinnati, losing in the first round, after his heroics at Wimbledon in which he reached the fourth round despite struggling badly with a back injury, the latest in a catalogue of woes he's suffered all year.
The seven winning nations in the September qualifiers will join defending champions Italy at the Bologna in 'final 8 week' between 18-23 November.
Among the team nominations, de Minaur has been joined by several other top-10 stars, headed by Spain's Carlos Alcaraz, Americans Taylor Fritz and Ben Shelton, and Denmark's Holger Rune.
Alcaraz and Rune will face off in a blockbuster Spain-Denmark clash in Marbella, while the Americans have a hugely powerful squad, also bolstered by Tommy Paul and Frances Tiafoe, to take on the Czech Republic, who are led by Miami champion Jakub Mensik.
