Postecoglou arrived at the City Ground in September following the departure of Nuno Espirito Santo and has overseen just six matches. The Australian, who guided Tottenham to the Europa League title last season, is still searching for his first win with Forest.
Frustration among the supporters has already surfaced, with chants of "you're getting sacked in the morning" ringing out during Thursday's 3-2 Europa League defeat to FC Midtjylland.
Despite that difficult start, Howe praised his opposite number's record in the game. "Ange is an outstanding manager with a good track record, it is a big match for us," Howe said.
The Newcastle boss also reflected on the realities of the managerial role. "I think we all know when we go into the job the fragility of it really. No amount of success previously can take you out of that firing line. We're all in it, we're all dictated to by results.
"But I think in any moment, good or bad, you've just got to be yourself, which Ange very much is," he added.
Postecoglou has won trophies in Australia, Japan, Scotland and England, but he has struggled at St James' Park. His Tottenham side lost both visits to Tyneside, conceding six goals and scoring once.
However, he did claim a 4-1 home victory against Howe's Newcastle in December 2023.
Newcastle are favourites for Sunday's contest, though Howe's side are also under pressure. The Magpies have collected just one win from their opening six league fixtures and will be desperate to secure three points before the international break.
After facing Forest, Newcastle will return to Premier League action away at Brighton on Saturday, 18 October.
Mikel Arteta has described Granit Xhaka as "one of the signings of the season" ahead of Arsenal's reunion with their former midfielder when they face Sunderland at the Stadium of Light on Saturday.
Strasbourg's on-loan defender Mamadou Sarr has chosen to represent Senegal at international level despite having represented multiple France youth teams.
Jadon Sancho's struggles deepened on Thursday night as the on-loan Manchester United winger failed to seize his opportunity in Aston Villa's 2-0 victory over Maccabi Tel Aviv.
Oliver Glasner has praised Crystal Palace's fighting spirit but admitted his side "still have plenty to improve" despite a commanding 3-1 home victory over AZ Alkmaar in the UEFA Conference League.
