The Real Madrid loanee lauded the dominance that the centre-back shows for Dortmund and says Pierre-Emerick Aubameyang is proving his quality
Hummels returned from injury in the Schwarzgelben's 2-1 win at Eintracht Braunschweig on Friday, which was their first win in five Bundesliga matches.
Sahin, who is coming towards the end of his 18-month loan from Real Madrid, lauded the impact that the 25-year-old Germany international has on Jurgen Klopp's side.
"Hummel is just a very dominant figure on the pitch," the midfielder, 25, told Kicker.
"His presence and his charisma help us. I can 10 feet play further forward, which makes it much easier for me to play well."
Sahin also praised summer signing Pierre-Emerick Aubameyang, who scored both of Dortmund's goals when they defeated Braunschweig last week.
"He's a great guy and his self-confidence is uncanny," the Turkey international of the former Saint-Etienne forward. "He very often instinctively does the right thing.
"He has shown in France that he's always scored a lot of goals. It's an indicator of his high quality."
Dortmund's next clash is Saturday's visit to Werder Bremen as last season's Champions League runners-up look to close the four-point gap between them and second-placed Bundesliga side Bayer Leverkusen.