The collaboration of two of the most widely popular stars, "No Doubt" front lady Gwen Stefani and controversial rapper Eminem, to create the theme song for Jake Gyllenhaal's upcoming flick with Rachel McAdams and Forest Whitaker, "South Paw," will definitely be one of the most highly anticipated singles of today. Speaking with Entertainment Tonight, Stefani shares her experiences working with the "Rap God" singer.

Describing Eminem, otherwise known as Marshall Matters, as "incredible," the mother of three also shared that the rapper is truly gifted and admirable especially with his mastery of his craft. She gushed, "He's so incredible." Stefani went on to say, "He's a real artist. He's a real weirdo."

Gavin Rossdale's wife further revealed that she has been constantly aiming to work with Eminem as she believes that the rapper is a "genius." She shared that her involvement with the project made her feel "honored" as she is well aware of Eminem's reputation of being really "selective" when it comes to choosing artists he wants to work with. She said, "I wanted to do something with him for so long and I feel honored - he's very selective. I feel really honored."

Although one would assume that getting two of the biggest names in the industry to work together would require quite some organized planning, Stefani disabused her fans and followers of that notion as she shared that her collaboration process with Eminem was actually quite "simple." She recalled, "The process was really simple." Stefani added, "One of his guys came and played me the song and then I was like, 'Yeah, I like it! Amazing!'"

She went on to say, "I just finally got the call. It was one of those days where they were like, 'Can you come do this?' And I was like, 'Really? Really?' And they were like, 'It has to be done today.' And I was like, 'Ok!' And I just made it happen."

While the part where she had to go and meet Eminem appeared to be uncomplicated, matters quickly became quite challenging on the day of the recording itself. Stefani recalled the issues that arose on the set date, and just how anxious she was to deliver something worthwhile. According to the singer, she unexpectedly suffered from a coughing fit which consequently affected her voice.

"The Voice" judge shared, "I went down there and my voice happened to not be working that day, and I was like, 'Ok perfect -- like, the one time I get asked to be on the Eminem song!?' I don't know - I just prayed really hard and the engineer made it come to life," Stefani said, according to Entertainment Weekly.