Metallica performed the first Big 4 show in the US over the weekend and bassist Robert Trujillo said they're only going to get better on their studio albums – and they have a few more records in them yet.

Thats great news for Metallica fans!  Trujillo says his band will be returning to the studio with producer Rick Rubin, and plan to do more than just one more album.

I love working with Rick. To me he’s a sort of Zen guru spirit that Metallica needs. We’re getting on incredibly well and we’re really excited about writing new music.

There’s no shortage of riffage in Metallica world right now – and I think it’s only going to get better. I know we’ve got another couple of records in us, and I think there’s a demand. It seems like we’ve got some new fans and they’re waiting for new music.

The first Big 4 show in the US featuring Metallica alongside fellow thrash giants Slayer, Megadeth and Anthrax. The event included another rendition of Diamond Head’s Am I Evil starring members of all four bands, and also featured a brief return for Slayer guitarist Jeff Hanneman, who’s still recovering from a flesh-wasting viral attack.

Just before all members took to the stage James Hetfield told the crowd:

We want to say thank you to all the metal fans out there who have supported all the bands, not just the Big 4. There’s a lot of great bands out there and we’d like to celebrate all of them.