When Tom Selleck appeared as a guest on Friends, he was “scared to death.”

The 77-year-old actor, who has played the courageous police commissioner on Blue Bloods since 2010, admitted in an interview with The Kelly Clarkson Show that he was terrified of playing Dr. Richard Burke, Courteney Cox’s character Monica Geller’s short-term boyfriend.

The reason, according to the heartthrob, was that he had never done a comedy series before.

The TV tough guy admitted to talk show host Kelly Clarkson that working on Friends was intimidating at first because he had never worked on a sitcom before.

“The most difficult thing is to be a guest on a show,” said the actor.

Referring to his reservations about joining the troupe, which included not only Courteney but also Jennifer Aniston and Lisa Kudrow, on the highly-rated sitcom with David Schwimmer, Matt LeBlanc, and Matthew Perry in 1995, he explained, “I was scared to death.”

I had done [an episode of] Taxi before, but I had never done a sitcom. As a result, I was extremely nervous.

However, the journeyman actor went on to say that his co-star, Courteney, was a “huge help” in welcoming him to the set.

Courtney was extremely helpful.

But that group of friends is amazing. They certainly became friends, both in real life and on the show. and it’s obvious. It was a fantastic place to work.

Tom was only meant to appear on the sitcom for three episodes, but despite the fact that Richard and Monica eventually split up, he appeared in nine episodes between 1995 and 2000.

The veteran actor stated that he uses his experience to put others at ease. “I try to calm the new actors because it’s really difficult to join a show where everyone is up to speed.”

For his appearance on the talk show, the actor wore a dark blue three-piece suit and tie with a lighter blue shirt in the style of Frank Reagan. He also had a salt and pepper goatee underneath his signature mustache.

When asked about his stache, the actor said, “Before Magnum, I worked most of the time without it.” Perhaps that’s why I did six unsold pilots.