Simon Cowell's protege Leona Lewis lights up the stage at the X Factor USA final

The last time he emerged from an X Factor final as a winning mentor, Leona Lewis was the act who came out on top.

So it’s no surprise Simon Cowell was an especially happy man tonight as he had his two favourite girls in one place.

I'm back: Leona Lewis returned to the X Factor stage this evening as she performed at the X Factor USA final

Simon's other lady: The 26-year-old won the British version of the show back in 2006 with Cowell as her mentor

Christmas star: Leona performed a heartfelt rendition of Snow Patrol's Run in a black maxi dress with flesh-baring side splits

The new Leona? Melanie Amaro become the first winner of the X Factor USA, scooping the $5 million prize

That's my girl: Following the song Simon said he was glad Lewis won the U.K edition of the programme in 2006

Back in the day: Simon with Leona on the night she won the British X Factor in 2006