Let's start with the encore.

It was that good.

In fact, it may have been the best halftime show this side of the Super Bowl. It peaked, of course, with "25 or 6 to 4." Except this was a concert, not a sporting event.

At the end of the night Saturday at Xcel Energy Center in St. Paul, co-headliners Chicago and Earth, Wind & Fire took the stage together and alternated songs on the encore, with both bands participating on every number.

EWF's "September" brought the near-capacity crowd of 14,000 to its feet. Chicago's strikingly funky "Free" kept the party going, and EWF's "Sing a Song" had everyone singing along.

EWF's hyperkinetic bassist, Verdine White, made sure everyone cared about Chicago's "Does Anyone Really Know What Time It Is?" EWF's "Shining Star" brightened the party. And then came the ultimate half-time song — Chicago's "25 or 6 to 4," propelled by two spirited bands of kindred spirits. What force, what uplift, what joy.

These are indeed emotional times for both veteran horn-accented groups with three original members and multiple lead singers that started in the Windy City in the late 1960s. EWF lost its founder and guiding light, Maurice White, in February, even though he'd stopped touring in 1994 due to Parkinson's disease. Chicago will finally be inducted into the Rock and Roll Hall of Fame this week after being eligible for 22 years; drummer Danny Seraphine will join them for the first time in nearly 25 years, but singer Peter Cetera, who left in 1985, will not.

This is the fourth time Chicago and EWF have teamed up on a tour since 2004. Saturday was bookended with joint performances, meaning 21 musicians onstage, including six horn players and as many as six percussionists. Even though the two bands are stylistically disparate, there was a commonality in tone for their separate 70-minute sets: Positivity, good-time vibes and terrific arrangements.

With countenances suggesting they still might be grieving, main singer Philip Bailey and bassist White, Maurice's brother, led EWF through a performance filled with spirit, spirituality and nonstop hits from the 1970s and '80s.

At 64, Bailey still has a rangy, deliciously soulful voice, with a gorgeous falsetto. White's vibrant energy, funky bass lines and even funkier clothes (his silver lamé baggy pants had enough fabric to cover a sectional couch) kept things moving. And the group's high harmonies were a heavenly sound to behold.

EWF is one of the few groups that can bring fans to their feet for ballads, which happened for "That's the Way of the World" (during which photos of Maurice White were projected on big screens behind the stage), "After the Love Has Gone" (during which an emotional Bailey sang with his eyes closed) and "Reasons" (during which Bailey unleashed three piercing, glass-shattering high notes, each one higher than the last).

EWF's disco-era hits "Boogie Wonderland" and "Let's Groove" didn't sound dated because there's a sophisticated jazziness to the group's dance-funk. No wonder this band made it into the Rock Hall in 2000.

Like EWF, Chicago sounded tight, polished and spirited. But the nine-member band lacked stage pizazz (though hammy trombonist James Pankow tried) and stellar lead vocals. Robert Lamm's voice sounded gruff, Jason Scheff's sounded pitchy and shrill, and Lou Pardini's sounded as if he'd taken enunciation lessons from Michael McDonald.

Chicago's early horn-propelled hits including "Make Me Smile," "Saturday in the Park" and "Questions 67 and 68" fared better than 1980s soft-rock ballads "You're the Inspiration" and "Hard To Say I'm Sorry." The concert reinforced the notion that Chicago had gone from progressive jazz-rock fusion to regressive schmaltzy pop balladry.

It's unlikely that Chicago will undergo a hipster reassessment with its entrance into the Rock Hall. At least, maybe EWF can join them to spice up the induction ceremonies.