“Tonight we’re playin’ straight-ahead jazz,” the alto saxophonist Lou Donaldson declared last evening, during his first set at Jazz Standard. “No fusion, no confusion,” he added, a hip, knowing tone in his voice.

Donaldson announces this at every one of his shows, as far as I know. Yet it never sounds canned, which is especially impressive because at the age of 85, Donaldson has been saying it to audiences for decades now. Though he now moves slowly, his mind is still agile, and his performances are punctuated with bursts of his old-fashioned sense of humor, which, combined with the soulful music he blows through his horn, make them a delight. Much like Louis Armstrong, Donaldson knows how to be an artist and an entertainer at the same time; he belongs on the stage.

And that’s where you’ll find him through Sunday: at Jazz Standard, performing with his quartet, which on Thursday included Eric Johnson on guitar (filling in for Randy Johnston), Pat Bianchi on Hammond organ, and Vincent Ector on drums.

Last night’s show was not all that well-attended, and it felt like an injustice. Donaldson was, last month, named a “Jazz Master“—along with Mose Allison, Eddie Palmieri and Lorraine Gordon—by the National Endowment for the Arts. It is considered the nation’s highest honor in jazz, and Donaldson deserves it.

In 1953, Donaldson played in several sessions for Blue Note with the trumpeter Clifford Brown that some believe to be the first hard-bop recordings. (The album released from those sessions is now called Memorial Album.) Later that decade, he put out a string of very good post-bop recordings—with piano, bass, drums, and congas. Most notable of those is Blues Walk, whose title track he used to open Thursday’s set.

Around that time, too, Donaldson was playing organ jazz, appearing on albums with Jimmy Smith, the best of which might be The Sermon, the title track of which runs just over 20 minutes, propelled by Art Blakey’s epic shuffle beat. In the late ’60s, expanding on the gutbucket qualities of Jimmy Smith’s music, Donaldson found some popular and financial success with his soul-jazz album Alligator Boogaloo, which drew heavily from rhythm-and-blues and funk.

 Some might look down on the direction Donaldson took next, when, in the late ’60s and much of the ’70s, he followed the success of Alligator Boogaloo with a series of mainstream-inflected recordings. For about 10 albums he dabbled in funk and disco, covering songs by James Brown, the Isley Brothers and Curtis Mayfield. The music didn’t always sound like jazz, but in Donaldson’s soloing, you heard a musician who had spent his career invested in the blues and the jazz ethic of improvisation. You still hear that. Donaldson has always been, at his core, a solid hard-bop musician.

That’s why the music he made during this time doesn’t feel disingenuous. It grooves. And to me, it just represents his desire to please the crowd, although he was following the money, too. (And it paid off, literally: In the last couple of decades, Donaldson has enjoyed a heap of financial success as singers like Madonna, Mary J. Blige, and Dr. Dre have all chosen to sample his work.)

Donaldson played the title track from Alligator Boogaloo on Thursday, adding the cryptic joke that “it was a big hit in Afghanistan.” Johnson left the stage during his own solo and walked casually among the audience, playing bluesy licks on his cordless guitar, imbuing a high-end jazz club with a barrelhouse feel. Donaldson looked on, squinting into the stage lights, a pleased expression on his face.

Donaldson is still capable of tearing through the chord changes of a brisk bebop number, as he did on “Wee,” a Charlie Parker anthem. But on ballads, his gorgeous tone, sweet and slightly tannic, really comes out. In his old age, the saxophonist resembles the late Johnny Hodges in appearance, and he sounds like him, too, tagging his phrases with breathy vibrato.

“We’d like to pay homage to the greatest musician of all time,” Donaldson said, before playing a slow rendition of “What A Wonderful World,” the Louis Armstrong standard. After the song, Donaldson went into an anecdote about the trumpeter. Louis Armstrong, he explained, “called everybody ‘Pops’ because he couldn’t remember their names.” (The jazz trumpeter Red Allen, he added, named musicians “by the city he met you in.”)

And a bit later, Donaldson sang, with his slightly metallic voice, “Whiskey Drinking Woman,” a song he wrote with the organist Leon Spencer. His band played a short instrumental introduction, after which Donaldson announced: “That is the blues, ladies and gentlemen. It’s called sufferin’ music where I come from,” which is the tiny Piedmont plateau village of Badin, North Carolina.

Then, in what seemed to be an ad-libbed section of the song, he devoted a good amount of attention to erectile dysfunction—though he never used those words:

“I tried Viagra, and the first time it didn’t work,” Donaldson sang. “I tried Cialis, didn’t work. I tried Levitra, didn’t work.” When he tried them all at once, Donaldson continued, you can only imagine what happened. The audience laughed.

“Glad to see that you appreciate classical singing,” Donaldson deadpanned when he finished.

At the set’s end, a man in the crowd yelled out a request. Donaldson didn’t fully hear him and asked him to repeat it. It was a call for “The Sermon.”

“That’s hard to play,” Donaldson said, with some hesitation. “And plus, it’s too long,” he added.

“I have time,” the man replied.

Donaldson paused for a moment: “Well, you know, the customer’s always right.”

He counted off and the band dove in.

Lou Donaldson plays at Jazz Standard Aug. 3-5. Tickets are available here.