As a crucible, the act of guest conductor meeting orchestra may be uniquely tricky. The conductor's path to self-actualization lies rather deceptively in coaxing the ensemble to become the highest form of itself.

It's not a spiritual exercise but a practical one when an ensemble's identity is as strong as the Philadelphia Orchestra's, which is why Susanna Mälkki's debut with the Philadelphians on Friday afternoon was remarkable. She seamlessly handed off woodwind timbres into strings in Respighi's Botticelli Triptych. If Brahms' Symphony No. 4's first movement seemed curiously bloodless in its stepped-down tempo, she revealed good reasons. At 45, Mälkki, who takes over the Helsinki Philharmonic Orchestra in 2016, is a blend of strong-willed and wise, yet there is nothing steely about her. Her high regard for the orchestra as a personality to cultivate makes her a bright prospect.

What she had to work with was sometimes subpar. It wasn't an occasional chipped note that was worrisome but clarinetist Samuel Caviezel, who declined to play out in moments that called for it, and principal flutist Jeffrey Khaner, whose tone is less burnished than it should be. Decorum demanded Mälkki grant him a bow for his weirdly stop-and-go solo in the Brahms' last movement, but it was hard to tell what exactly he was going for, or why.

And yet this Brahms Fourth was strongly wrought and fastidiously realized. Mälkki beautifully rode restraint's coiled potential. In the first movement, the slower tempo came with subtle phrasing but ultimately yielded to moments of fury in surprising places. Nothing was obvious, yet her individualism was born of deference to the score.

The question of individualism always arises when the orchestra turns to its own ranks for a soloist, and Juliette Kang, first associate concertmaster, was sturdy enough in the Stravinsky Violin Concerto in D Major. Astringent and playful, the piece looks back on the baroque, an aspect Kang clearly understood, though as soloist she remained a notch beneath charismatic.

A word about the Respighi. Yes, it's trite. Mälkki and the orchestra, however, elevated it through gorgeous phrase-shaping, meticulous attention to repeated rhythmic figures, and a glowing ensemble sound. When a conductor does great things with a second-rate piece, she is someone to take seriously.