Since being founded in 1994, the Foo Fighters have sold millions of albums, won multiple Grammys and performed in front of stadiums packed with fans. But none of that would have happened if Dave Grohl -- the band's guitarist and founder -- had taken a once-in-a-lifetime opportunity to join Tom Petty and the Heartbreakers.

Back in 1994, Grohl -- who turns 48 today -- was still reeling from the abrupt death of former Nirvana bandmate Kurt Cobain. At the same time, Tom Petty found himself short a drummer when Stan Lynch -- one of the founding members of The Heartbreakers -- quit the group. 

So Petty reached out to Grohl and asked him to fill in on the skins for a performance on Saturday Night Live. 

The experience was a dream come true for the longtime Petty fan.

"As an American kid, he was the guy you looked up to and you want to be like Tom because Tom's cool," Grohl later told the BBC.  

That guest spot almost became a permanent gig. After the set, Petty allegedly offered Grohl a permanent spot with the Heartbreakers. Grohl turned him down so that he could focus on his own music. 

But don't blame Petty for nearly wrecking the Foo Fighters before the group formed. Grohl might not have gone ahead with that new project if playing with the Heartbreakers hadn't made him feel good about playing for the first time since Cobain's death.

"It was the first time that I had really looked forward to playing the drums since Nirvana ended," Grohl later said. He would go on to play the drums and every other instrument on the Foo Fighters debut album later that year.

And showed off some acting chops in the band's videos.