Shaky Knees? More like muddy paws or waterlogged sneakers.

No, the weather did not provide a courteous welcome to the inaugural Shaky Knees Music Festival. But that didn’t deter several thousand fans (the numbers intensified as evening approached) from trekking down to Fourth Ward Park/Masquerade Music Park for 10 hours of music for the first of the two-day event.

From an early set from Texan Robert Ellis – who performed George Jones’ “The Grand Tour,” a song he’s been playing long before the Possum’s recent death – to the closing musical bash by Band of Horses, Shaky Knees maintained its promise to bring an indie rock fiesta to Atlanta.

Of course it would have been preferable had the weather somewhat complied instead of dumping a monotonous stream of water on concertgoers, most of whom quickly realized the value of a plastic poncho and the reality that they would spend several hours shivering and trying to avoid face-planting in the molasses-thick mud.

But most seemed to adopt a “what can ya do?” attitude and happily drank with friends, kicked up the watery dirt as they danced, and hooted and hollered through most of the sets taking place on three stages around the parks.

Of the day’s music, which also brought the rock-soul of Hanni El Khatib, the lo-fi punk of impressive young Illinois band The Orwells and the Euro-alt-rock of The Joy Fordmidable, Gary Clark Jr. and J Roddy Walston and the Business rocked opposite ends of the park for different reasons.

The elegant-looking Clark, often referred to as his generation’s Jimi Hendrix (for good reason), jammed with his three-piece band on the swinging blues-rocker “Don’t Owe You a Thang,” tossing out blistering solos with jaw-dropping ease.

Later in his hour-long set, Clark unleashed the mesmerizing “When My Train Pulls In” which dovetailed into a lengthy jam that had the soggy crowd roaring.

Meanwhile, the Baltimore-based J Roddy Walston and The Business soared on singalongs “Full Growing Man” and “I Don’t Want to Hear It.”

These guys might look like car mechanics, but they sound like an amalgamation of Queen, Gaslight Anthem and Mott the Hoople. Walston was an engaging frontman, bopping from piano to guitar and singing in a growly, charismatic voice and turning the assembled throng on to the new song, the instantly engaging “Hard Times.”

While Walston and Co. pounded away, My Morning Jacket frontman Jim James, decked out in a suit and tie, floated through his jammy dreamscapes including “Know ‘Til Now” (complete with sax) and “Dear One” from his recently released solo album, “Regions of Light and Sound of God.” With a sunburst of light behind the stage and a killer drum solo from David Givan adding some rock heft, it was easy to believe James when he told the crowd, “I can feel your spirit.”

Shaky Knees continues on Sunday starting at 12:50 p.m. with a set from Atlanta’s magnificent sister act, Von Grey. Headliners include The Lumineers and Drive By Truckers.

Click here for a full lineup and more info. And here’s to drier times.

(AJC audience specialist Yvonne Zusel contributed to this report.)