"This category seems to be a toss-up between Lorde and Macklemore & Lewis," Bovada sports book manager Kevin Bradley told MTV news.
"We think Macklemore & Lewis are the runners up here because they are more likely to win in other categories. We think Grammy voters will spread the love and give this one to Royals."
According to bookies, Lorde is also a front runner to win in the Record of the Year category. Bovada is quoting Royals as 8/5 second-favourite behind Daft Punk's anthem Get Lucky, which is offered at 5/4.
"A lot of possible upsets here, but we like Daft Punk in this category," Bradley said. "They came back from a long absence to revive their spot in dance music and create one of the year's most inescapable hits."
In the build-up to tomorrow's glamour awards, Lorde sang at an intimate concert on Friday (NZ-time) and reminded the crowd to tune in to her performance at the Grammys.
The 17-year-old performed for a tightly packed crowd at the Soho House in Los Angeles. She thanked fans for watching and said she hoped they would be watching tomorrow.
Lorde kicked off the show with Glory and Gore and later played Royals.
Chart-topper Royals is also up for Best Pop Solo Performance at the Grammys, and Lorde's debut Pure Heroine will compete for Pop Vocal Album.
Lorde will be joined at the Grammys by her New Zealand producer and co-writer Joel Little, who is nominated for two awards.
• Watch the 56th Annual Grammy Awards at 2pm live on TV2.
