Hewitt's men had faced the nervy prospect of having to go into Sunday's final group match against hosts Germany in Hamburg with qualification for the competition climax in Malaga in November still not guaranteed despite their two wins this week over France and Belgium.
But Germany's hard-fought 2-1 victory over the Belgians on Friday was enough to ensure Australia will be among the eight quarter-finalists who'll take their place among the elite for the knock-out climax to the event in Spain.
It's great news for Hewitt, whose team will now be battling with the hosts on Sunday to simply top the group, as both teams have guaranteed their Malaga places, while France and Belgium have both bowed out.
It will give him the opportunity to give Thanasi Kokkinakis a run-out without any pressure should Hewitt's No.2 ranked player be fit enough after a week in which he has felt under the weather and was replaced by debutant Jason Kubler.
If Australia end up winning group C, they'll play the runners-up of group B, which could be Serbia, Canada or hosts Spain, featuring Carlos Alcaraz, whose first match as world No.1 ended with a 6-7 (3-7) 6-4 6-4 loss to Canadian Felix Auger-Aliassime in Valencia on Friday.
If Hewitt's side end as runners-up, they'll play the winners of group D, which will either be USA or the Netherlands, both victorious in their first two matches.
On Friday, Germany's tie on their home court in the Rothenbaum Stadium went down to the wire in the doubles just as it had done in their opening win over France.
Jan-Lennard Struff had put Germany ahead with a 6-4 7-6 (11-9) win against Zizou Bergs, but David Goffin's 3-6 7-6 (9-7) 6-3 triumph over Oscar Otte, in which the Belgian saved two match points, proved a courageous equaliser.
Once again, Kevin Krawietz and Tim Putz secured victory for Germany by beating Sander Gille and Joran Vliegen 4-6 6-2 7-6 (7-5).
Should Sunday's tie come down to the doubles, they'll be facing a similarly excellent doubles combo in the Aussies' Wimbledon champions Max Purcell and Matt Ebden, who've won their first two rubbers without losing a set.
9°C