Concert: Tom Petty & The Heartbreakers and Crosby, Stills & Nash in Hartford, CT

In quick succession, Petty zipped through "Listen to Her Heart," a funky "You Don't Know How it Feels" and "I Won't Back Down." Next up, the trademark introductory chords of "Free Fallin'" brought shrieks and the first evidence of audience participation as the crowd finally seemed to catch on that the headliners had arrived.

Shedding his guitar, Petty then prowled the stage, conducting his band with maracas and lending necessary accompaniment to a blistering cover of Fleetwood Mac's early blues tune "Oh Well." "Last Dance with Mary Jane" wove layer upon layer of nuanced rhythms into the repetitive, descending chord structure as Campbell finally seemed to hit stride.

But at the song's end, Campbell's amp rig again crapped out temporarily, leaving Petty to opine about "blowing up the amplifier Mike bought from Sears." A few moments and an instrument change-out later, the band was back on track, with the unflappable Campbell smiling and shaking it off with a smirk.

A trio of songs from Petty's latest project, "Mojo," provided opportunities for the band to explore new avenues. "Jefferson Jericho Blues" had a nice chuga-chuga rhythm, while "Good Enough," got down and dirty with a progression reminiscent of Screaming Jay Hawkins' "I Put A Spell On You."

"I Should Have Known It" switched to a Led Zeppelin feel, with Campbell wringing as much soul out of his Les Paul as Jimmy Page ever did in his heyday. Petty's set wrapped with a powerful pre-encore "Refugee" and sent the crowd home with back-to-back rockers, "Runnin Down a Dream" and "American Girl."

It was Steven Stills who commanded much of the attention during the opening set by Crosby, Stills & Nash.

Looking somewhat gaunt -- perhaps from significant weight loss following a 2008 battle with prostate cancer -- neither Stills' road-hardened voice nor his guitar playing seemed to be affected. He dealt an unstoppable litany of crisply articulated guitar leads and riffs, never missing a beat. His vocals, especially on "Bluebird" and the encore "For What It's Worth," were also strong and confident.

Besides an acoustic cover of "Ruby Tuesday" and the audience favorite "Our House," CSN's set was electric and loud. The volume of the instruments, however, did not mask the famously tight harmonies -- particularly strong this night between Crosby and Nash, although the trio's vocal work on "Deja Vu" was particularly intense.

"Southern Cross," more recently and famously covered by Jimmy Buffett, seemed to bring all the Parrotheads in the crowd immediately to their feet and prompted a raucous sing-along. That number also featured Crosby and Nash's tastiest guitar work of the set.

Besides Stills' consistently top-flight guitar, keyboardist Todd Caldwell was also a huge contributor with his expressive work on the Hammond B3 organ -- specifically on "Wooden Ships," which wrapped up the main set.