NEW YORK — Sometimes it seems as if good things can occur in Chris Gethard’s life only if they are balanced out by other, inauspicious events. On Friday afternoon, Gethard, 30, a boyish comedian with a gentle disposition, was playing basketball when another player collided with him, breaking his glasses, cutting his nose and sending him scrambling to LensCrafters for some emergency repair work.

On the other hand, Gethard ended his day by performing in a comedy show with Diddy, the illustrious if elusive hip-hop mogul, after a campaign that lasted more than a year.

At about 11:30 p.m. Gethard could be found in his mended glasses, pacing in his pea-green dressing room. He had been told Diddy would be arriving soon, but then he had broken promises to Gethard in the past, and he was trying to keep his expectations in check.

“He just lives on a different planet from me,” said Gethard, who was drinking from a 16-ounce can of Red Bull and repeatedly applying ChapStick to his lips. “I have no idea why he’s doing this.”

Then, through a back door, Diddy arrived, as unassumingly as one could enter a room with a hulking bodyguard (as well as an assistant and his teenage son, Justin). Dressed casually in a thermal shirt and jeans, Diddy (whose real name is Sean Combs) introduced himself to Gethard and the other comedians he’d soon be performing with. They chatted about the night’s routine, and Gethard warned Diddy not to take offense at anything in the show.

“That’s good,” Diddy replied, “because I’ll talk about everything.”

And then it was showtime. “I’ve had 13 months to think about this,” Gethard said. “Let’s see if we can get it right.”

These have been some up-and-down days for Gethard, a performer who is well known within the insular world of improvisational comedy but hardly a household name. In April, he was seemingly plucked from out of nowhere — or maybe his hometown, West Orange, N.J. — to replace Jon Heder, the “Napoleon Dynamite” star, in the Comedy Central series “Big Lake” when Heder abruptly dropped out of the project. Though “Big Lake” came from the production company of Will Ferrell and Adam McKay, comic kingmakers who are fans of Gethard, the show seemed to fizzle after its August debut, and Comedy Central has yet to order more episodes.

Months earlier, at the end of 2009, Gethard took to the Internet in an aggressive effort to persuade Diddy to take part in “The Chris Gethard Show,” his midnight showcase at the Upright Citizens Brigade Theater. (This was after Gethard was rebuffed by Al Roker, the chummy “Today” show personality.)

After Gethard fired off tweets to Diddy and posted video appeals on YouTube, Diddy responded on his own Twitter account that he would appear in Gethard’s show some time in 2010. (“He sounds like a pretty cool dude!” Diddy wrote.)

But one Winter Olympics, one World Cup, a few Lindsay Lohan court appearances and one year later Diddy had still not made good on his vow. In a September interview on “Late Night With Jimmy Fallon,” Gethard announced that if Diddy attended a special paintball-theme show at the Upright Citizens Brigade Theater “he can shoot unfunny comedians.” But Diddy still did not pull the trigger on the invitation.

The turning point came in December, when Diddy appeared on “Saturday Night Live” with his group Diddy-Dirty Money, and Gethard used a connection at “SNL” to get into the show and confront him there.

“I think it was just his persistence,” Diddy said backstage on Friday night, explaining why he finally gave in to Gethard. “I was, like, ‘Who’s this guy?’ But I felt his energy and his spirit. I’m supposed to be at the Golden Globes right now, but I’ll just go there a little bit later.”

Beginning at about 12:20 a.m., the performance Diddy participated in was equal parts talk show, improv show and Friars Club roast, and if he did not quite bring the same explosive energy he displayed last year in “Get Him to the Greek,” he at least delivered the laconic comedy he brought to his 2001 film debut in “Made.”

By about 1:30 a.m. Diddy and his entourage had already left the Upright Citizens Brigade Theater, but Gethard and his colleagues could still be found backstage, gathering their belongings, surging with adrenaline and wondering if they’d get any sleep.

Gethard said it hardly mattered because he had to be in New Jersey at 9 a.m. to take a 90-minute class on using the bathroom in the RV he was renting. “That’s my life,” he said.