Messi scored once and assisted two others as Barca eased past Dortmund 3-1 and into the last 16 at Camp Nou on Wednesday.
It was a memorable 700th Barca outing for Messi, who set up Luis Suarez for the 29th-minute opener before his team-mate returned the favor four minutes later.
Five-time Ballon d'Or winner Messi then teed up substitute Antoine Griezmann with 23 minutes remaining to cap a stellar display, prompting high praise from Dortmund defender Hummels.
"In top form, Messi is the best footballer I have ever seen – period," Hummels, who gave the ball away for Messi's goal, said post-game.
"We were not good enough to beat Barcelona today. We only created three or four real chances."
Hummels added: "It was not a bad game, but not a very good one. Barcelona were excellent though. Messi is always dangerous, of course.
"We had a really bad spell after that first goal, with my bad pass that led to their second goal."
The result left Dortmund third and level on seven points with second-placed Inter heading into the final matchday in Group F.
Dortmund face Slavia Prague on December 10, while Inter welcome group winners Barca to Milan on the same day.