Las Vegas party the perfect Open warm-up for Koepka

SOUTHPORT, England, July 20 (Reuters) - A holiday with friends in Las Vegas and a four-week break from competitive golf proved the perfect British Open preparation for Brooks Koepka.

The 27-year-old American, who claimed his first major title at last month's U.S. Open, carded a five-under-par 65 in tough conditions at Royal Birkdale on Thursday to share the first-round lead with compatriot Jordan Spieth.

And he put a lot of it down to the Vegas trip.

"It was fun, I had a few friends out. We had a good time," Koepka told reporters.

"Getting back to the gym was tough, but if I'm mentally recharged then so is my swing. I've done the same thing for years."

Koepka parred his first seven holes before a run of three successive birdies from the 11th. He dropped his only shot of the day at the 16th before chipping in from a bunker to make an eagle at the 17th.

"I felt like I was in control of the golf ball pretty much all day," he said. "It was just fun to get back playing again. After taking four weeks off, it's nice to get back inside the ropes and finally get those competitive juices flowing."

Unlike some American players who grow used to the manicured layouts on which the majority of U.S. Tour events are played, Koepka is a big fan of links courses and the tougher weather conditions often experienced at the British Open.

"I love links golf," he said. "So anytime I can come across the pond and play links it's special."

Koepka said he felt no extra pressure following his U.S. Open triumph at Erin Hills.

"It was still the same me," he said. "I'm not going to change. You've just got to hit a golf ball, that's all you have to do. It's not like it's a sense of relief."

Twice a winner on the U.S. PGA Tour, Koepka said he hoped to add more majors to his trophy cabinet.

"I'll maybe look back at the end of my career and be extremely satisfied or disappointed. But as of right now I still have got a few more to win." (Reporting by Ed Osmond; Editing by Christian Radnedge)