A conductor must exercise something like a wrestling hold to embrace many a Mahler symphony. The Fifth is no exception, with its abrupt shifts of mood and tempo and its often stubborn refusal, or inability, to achieve clear and easy musical resolution. Daniel Barenboim is well-suited to the encounter. He patiently and sensitively paces the powerful Chicago Symphony so as to unveil the composer's seeming lurking regret and anger in the first two movements, a harbinger of the later symphonies. Barenboim also illuminates both the languid dreaminess of the fourth-movement "Allegretto" and the almost optimistic opening up of the final movement, which harkens back to the rustic folksiness of Mahler's earlier work.Chicago's brass and string players are Barenboim's allies in this challenge, bringing brilliant, rich coloring to the reading. Without such a level of articulation and phrasing, this volatile material would sound messy indeed.