Metallica star Lars Ulrich reportedly celebrated his impending nuptials by partying with pals in San Francisco, California over the weekend (28Feb15-01Mar15).

The drummer proposed to model Jessica Miller in 2013, and two years later, the couple is finally preparing to tie the knot.

According to People magazine, Ulrich invited his close male friends, including Bradley Cooper, Sir Ian MCKellen and Metallica frontman James Hetfield, out for dinner and bowling on Saturday (28Feb15).

An insider tells the publication they had their own private room in bowling alley Lucky Strike, where "Bradley was the top bowler."

Ulrich and his friends later went to a nearby restaurant for a celebratory dinner.

The upcoming nuptials will mark the third marriage for the rocker and the first for Miller. He has four sons from past relationships.