The inaugural Classic East festival more than delivered on its lofty promises — two nights of great music capped by headlining sets from Fleetwood Mac and the Eagles.

Fleetwood Mac’s set Sunday night at Citi Field was once thought impossible to see again after Christine McVie retired from touring in 1998. The Eagles set Saturday night was one never seen before in the area, with the late Glenn Frey’s son, Deacon, and Vince Gill stepping in to pay tribute to the band’s co-founder.

Both worked remarkably well.

Fleetwood Mac was definitely in crowd-pleasing mode early on, eager to show how great they sound with McVie back in the fold.

Their first four songs set the tone — all from “Rumours,” showcasing vocals from McVie, Lindsey Buckingham and Stevie Nicks, as well as a drum solo from Mick Fleetwood and John McVie’s steady bass work.

Buckingham said that even though the band’s legacy is often defined by their disagreements, “I think if you look beneath that, what you see is a lot of love.”

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And that’s what was on display, as they enjoyed themselves playing around on the experimental “Tusk” and adding new harmonies to “Sara,” which ended with a hug between Buckingham and Nicks.

Fleetwood Mac has always been an impressive balancing act, so when they followed a 10-minute “Gold Dust Woman” with a nine-minute version of “I’m So Afraid,” which did feature several great Buckingham guitar-hero moments, it seemed a little out of character. However, they quickly snapped back with a crisp, energetic “Go Your Own Way.”

The Eagles concert at Citi Field Saturday was so poignant and well-executed there was no way to tell whether it was the legendary band’s final East Coast appearance or the start of its next chapter.

Though the band served as the headliners for opening night of The Classic East festival’s high-profile inaugural run, its show was more a tribute to the band’s co-founder, the late Glenn Frey.

“It’s a little tender here,” said Deacon Frey, who joined the band to handle the lead vocals on some of the songs his father Glenn had written, adding that it was the first time he had returned to New York since his father died here last year at 67 of complications from ulcerative colitis. “It really means a lot to come back here and feel all this love.”

Both Freys got a huge ovation at the end of “Peaceful, Easy Feeling,” with a photo of Glenn showing on the huge video screens as Deacon delivered a touching version of his father’s signature song that would have made him proud. Deacon Frey’s vocals, especially on “Take It Easy” and “Already Gone,” are all the more disarming because the 24-year-old looks so much like his father from the Eagles’ heyday and his harmonies fit in so well with the rest of the band.

That said, his father’s absence is still deeply felt in the band. For decades, Glenn Frey did most of the talking onstage during Eagles shows and it felt strange to hear bassist Timothy B. Schmidt and guitarist Joe Walsh try to pick up that mantle. Singer-drummer Don Henley has said that this show, along with two West Coast versions of the festival, may be the band’s “last dance,” following Glenn Frey’s death, which is understandable.

However, there was plenty of fire left in the band’s performance Saturday night, with the addition of Deacon Frey and the great Vince Gill bringing a renewed strength to the Eagles’ trademark harmonies.

Gill took on the bulk of Glenn Frey’s lead vocals, shining especially bright on “New Kid in Town.” And the new blood in the band seems to have inspired the remaining Eagles.

Henley, with the help of a new horn section and a string section, offered a powerful version of the epic, rarely played “The Last Resort,” while his vocals on “Best of My Love” and the final encore “Desperado” were simply stunning.

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Whether or not this was the Eagles’ final area show remains to be seen, but it would certainly be a worthy bookend to the band’s legendary career.

It was also a fitting end to a stellar opening night for The Classic East, which began with a good time blues-rock set from the Doobie Brothers. Steely Dan offered a stylish mix of songs from throughout its career, enlisting guitarist Larry Carlton to fill in for the ailing Walter Becker, who singer Donald Fagen said was recovering from an illness.

FLEETWOOD MAC SETLIST: The Chain / You Make Loving Fun / Dreams / Second Hand News / Rhiannon / Everywhere / Bleed to Love Her / Tusk / Sara / Say You Love Me / Big Love / Landslide / Never Going Back Again / Think About Me / Gypsy / Little Lies / Gold Dust Woman / I’m So Afraid / Go Your Own Way // ENCORE: Don’t Stop

EAGLES SETLIST: Seven Bridges Road / Take It Easy /One of These Nights/ Take It to the Limit / Tequila Sunrise / Witchy Woman / I Can’t Tell You Why / Lyin’ Eyes / Those Shoes / Peaceful Easy Feeling / Best of My Love / Love Will Keep Us Alive / New Kid in Town / The Last Resort / Already Gone / In the City / Heartache Tonight / Life’s Been Good / Funk #49 / Life in the Fast Lane // ENCORES: Hotel California / Rocky Mountain Way / Desperado