The other "must-hit" was Republic’s bash at Catch, which had a crowd of invitees pouring out onto Melrose Avenue.

Inside, label co-founder /CEO Monte Lipman welcomed Grammy host James Corden and Stevie Wonder. After 1 a.m., Corden was a passing a tray of sushi around his crew.

Back at GQ, Chance stood right in the lobby of the Chateau greeting guests as they arrived.  In turn, Quincy Jones (center) and GQ Editor-In-Chief Jim Nelson nabbed the man on the cover of this month’s issue for a more private huddle.

Katy Perry made a wardrobe change from her “We the People” performance of new hit “Chained to the Rhythm” and cruised through Universal’s soiree downtown before arriving at Chance's victory party.

Snoop Dogg and Macy Gray surround the host.

Chance was still in the same blue sweater he wore on the telecast. A grab-your-own hat rack of the Chicago native’s signature “3” cap led to a crowd of clones within a few minutes.

Maren Morris and Ryan Hurd grabbed one of the choice perches in the center of the Chateau courtyard. Morris, who had a breakout moment performing on the telecast, was once rejected from both “American Idol” and “The Voice."

Ty Dolla Sign and Skrillex didn’t put on the “3” hats like everyone else, but they have been on Team Chance. Skrillex performed at Chance’s hometown “Magnificent Colorind Day” festival in Chicago last summer.

Before Chance and Migos rocked the living room, DJ Oreo (right) spun fellow windy city phenom Kanye's songs back-to-back for the Chicago-heavy crowd. “Homecoming” and “Runaway” warmed up the room for Migos as rapper Lil Yachty sat on top of the DJ booth.

Christina Milian and Snoop Dogg were spotted inside GQ, which was presented by YouTube.

Milian also had her girl squad: The Kanye video dancer who went viral (Teyana Taylor, center) and Milian’s frequent running mate Karrueche Tran -- the woman who ignited the Chris Brown and Soulja Boy celebrity beef boxing match.

GQ Publisher Howard Mittman was seen with Eric Ray Davidson -- the man who shoots a ton of the magazine’s celebrity profiles and occasionally moonlights as a cell-phone rescuer from the Chateau pool after rowdy GQ parties.

Also Read: Amy Schumer and Her Fantasy Bradley Cooper, Jon Hamm, Michael Keaton Celebrate GQ’s Men of the Year (Photos)

Meanwhile, over at the Republic party at Catch, The Weeknd and Stevie Wonder were two of the bold-face names packing the rooftop space.

Jason Derulo had been one of the first to arrive, eating dinner in Stevie Wonder’s reserved table before the Motown legend arrived.

The Fifth Harmony ladies were on the scene at the Fiji Water-hosted bash: Normani Kordei, Ally Brooke, and Lauren Jauregui.

Here is Jessie J and Joel Madden at Catch.

The crowd included a late-arriving Nicole Scherzinger, who came with Pussycat Doll founder Robin Antin.

Mr. Brainwash, Monte Lipman, and Universal Music Grouup CEO Sir Lucian Grange.

Heidi Klum and David Foster held down a banquette on the east-side patio...

...which overlooked this projection onto the Pacific Design Center next door.

Republic Group President Charlie Walk is seen with the much-taller-in-person Afrojack.  Once inside, the Ducth producer hung with Jessie Waits, the Vegas nightlife executive responsible for XS and Tryst who is opening up the reported $4-billion Alon project in the next few years.

Painted models were camouflaged, passing tequila sodas and Frexeinet Cava throughout the space.

Don’t sleep on Stanaj. The Republic artist's long-awaited EP recently arrived. His showcase packed the Sayer’s Club full of faces like Randy Jackson and Jason Flom before it even got dark out one summer night last August.

Anthony Mackie with Catch owner Mark Birnbaum, Nick Cannon, and model/actress Maya Henry held court in the room that also included Nicole Richie, Skylar Grey, and Aurora.

Adrien Brody and girlfriend Lara Lieto pose for a pic at Catch.

Grammys night brings together far flung corners of the industry under music's big tent. Here, Texas-based actress and philanthropist Maya Henry nests with French Montana and David Foster, who appreciated The Party Report's suggestion that the Grammys should do a tribute to his '90s film score for "Stealing Home."

Back off "Bachelor" Nick Viall. Your big nights are Mondays, not Sunday. 

Lines of annoyed invited guests were a common issue all over town. This was the scene at Republic. In addition to the Chateau (which was shut down temporarily during the performances), Warner Music’s event at Milk Studios reportedly hit capacity on the early side of the night.

Steve Aoki (with longtime pal DJ Vice on the right) celebrated the globe-trotting music mogul's Netflix doc "I'll Sleep When I'm Dead" at Bootsy Bellows.

At the Warner Block Party, Spencer Ludwig was one of three headliners, playing with Kehlani and Gallant. NFL QB Russell Wilson, Katharine McPhee, and Rita Ora mixed and mingled as the Rémy Martin flowed. 

At Warners, the Black Eyed Peas were one Fergie short of a reunion: Taboo, apl.de.ap, and will.i.am.  

From Adele to Beyonce, check out TheWrap's ranking of Grammy Performances from Best to Worst:

Also Read: Grammys 2017 Performances Ranked From Worst to Best: From Adele to Beyonce (Photos)