A lot of fans had mixed opinions about Christina Aguilera’s tribute to Whitney Houston at the American Music Awards on Nov. 19, with many leaning towards the negative end. Unfortunately, the late singer is unable to give her take on the performance, but her former vocal coach, Gary Catona, is and you may be surprised by his opinion.

Twitter quickly erupted in debate and controversy as Aguilera performed renditions of “I Will Always Love You” and “I Have Nothing.” But Catona, who previously coached Houston for years, told The Blast that he gives Aguilera’s tribute a "B-" overall, but an “A” effort.

Even so, he did find some issues with her pitch. “Whitney is the gold standard vocally and artistically, so in my opinion, Christina fell below that,” he said. “Christina had some pitch issues, phrasing difficulties and she over-used Whitney’s trademark ‘melisma’ singing.” 

He also thinks the “Lady Marmalade” singer would have benefited from a more simplistic approach. The voice coach, who helped shape the mega-star’s voice for her 2009 comeback album, I Look To You, said that he “would have advised her to sing the song in her own way and not try to copy Whitney as much as she did.” 

While he commended Aguilera for giving it her all, Catona noted that a singer like Adele could’ve pulled it off with much more precision. Nevertheless, Catona suggests that it’s nearly impossible to compete with Whitney Houston vocally, but he appreciated Aguilera’s effort.