Dortmund advanced past Frankfurt with a 1-1 draw after extra time, prevailing 4-2 in the penalty shoot-out to reach the last 16 of the DFB-Pokal.
With seven fixtures crammed into a hectic 22-day spell, Kovac admitted rotation will be essential to keep the squad fresh.
Speaking at his Thursday press conference, Kovac said: "That's normal. Stuttgart, for example, made 10 changes. You need that to maintain a high level. We have high-quality players, and that's part of football.
"We need physical and mental freshness, and I'm making use of that. I trust every single player."
Guinean forward Serhou Guirassy, who started on the bench in the cup match, is expected to return to the starting line-up despite enduring a quiet spell in front of goal. Kovac is also set to provide opportunities to players with limited recent minutes, as Dortmund aim to stay in contention with league leaders Bayern Munich.
The Dortmund boss gave an update on his squad, confirming that defender Niklas Sule remains doubtful after sustaining a knock, a swollen toe, against Frankfurt. "They came through the cup match well," Kovac explained. "The only one with problems is Sule. He has a swollen toe. Emre Can and Julien Duranville are making progress, and Ramy Bensebaini will return to the squad."
Dortmund, who sit fourth in the Bundesliga table, are coming off a 2-1 league defeat to Bayern Munich earlier this month but have since won their last three games across all competitions, and will be hoping to extend positive momentum when they travel to face Augsburg at the WWK ARENA.
