Madonna Says Lady Gaga Turned Down Duet Request

'I invited her onstage to sing with me. But she turned me down,' Madonna tells fans at a show.

Oh, that explains it!

Madonna has not been shy about taking swipes at Lady Gaga this year. Those digs have included not-so-subtle mocking of Mother Monster over the melodic similarity between "Born This Way" and Madge's 1989 hit "Express Yourself."

Now we might have a glimpse at why that animosity continues. During a show on Sunday in St. Paul, Minnesota, Madonna told her fans that she'd been spurned by Gaga after extending the hand of friendship.

"I have the best fans in the world. So take that, Lady Gaga! You know, I invited her onstage to sing with me. But she turned me down," Madonna said. "It's OK. I've been rejected before. It builds a little character."

While Madonna didn't elaborate on when this peace offering came, it might have cut the tension between the two, which has been simmering since last year.

Fans were quick to comment on the latest Madonna madness, with one posting on the Los Angeles Times website that, "The ironic thing ... Mad did the same thing to Cher."

On Billboard, fans were about equally divided, with one slamming taking Madonna to task for keeping the feud going, writing, "On another note, how do you think Madonna looks by using Gaga to stay [in] the news?"

Earlier this year, during an interview with ABC News, Madonna used the word "reductive" when referring to 'Born This Way." And on her MDNA tour, Madonna has played a mash-up of the two songs, ending with the refrain "she's not me."

To drive the point home, in July while appearing on a Brazilian TV show she joked, "I'm a really big fan of ['Born This Way']. I'm glad I helped Gaga write it."

Gaga has tried to stay above the fray and not engage the veteran pop icon, who has gotten blasted by her former friend, Elton John, for teasing the "Marry the Night" singer.

Perhaps the latest revelation could lead to a peaceful resolution, but Gaga would have to hurry up, since the MDNA tour ends on November 20 in Miami.