July 10 (Reuters) - Scotland's Colin Montgomerie, making the most of a "relaxed" grouping, birdied four of his last seven holes to seize an early one-shot lead in the opening round of the U.S. Senior Open in Edmond, Oklahoma on Thursday
Seeking his second major victory on the over-50s Champions Tour, Montgomerie racked up eight birdies and two bogeys to card a six-under-par 65 in rain-softened, relatively calm conditions at Oak Tree National.
The 51-year-old, a 31-times champion on the European Tour who played the opening round in the congenial company of Americans Rocco Mediate and Tom Lehman, finished one stroke ahead of another American, Marco Dawson.
"I was patient, I was relaxed," Montgomerie told reporters after covering his back nine in three-under 32. "We had a good time. I was happy with the pairing we had, the three who were playing together.
"We played a lot together over the first year of my Champions Tour life. But the statistics, you know, add up. Sixteen greens out of 18 (in regulation). Not bad statistics, really.
"And then 11 fairways out of 14. You'd take that. So, yeah, just a good run of golf. A good, solid round of golf today."
Germany's Bernhard Langer, who won the Senior Players Championship in a playoff in Pittsburgh last month, and American Kirk Triplett opened with 69s at Oak Tree where play was suspended for just over an hour due to thunderstorms.
Reigning champion Kenny Perry, the hottest player on the Champions Tour over the past year who landed his third consecutive seniors major title at the Regions Tradition in May, was among the late starters on Thursday.
Montgomerie, however, commanded the early spotlight after gaining a major jolt of confidence from his four-shot victory at the Senior PGA Championship in May when he broke his long American title drought in style.
The Scot, who never won on the regular PGA Tour despite a decorated career in Europe, fended off a mid-round charge from Tom Watson to clinch the second major of the season on the over-50s circuit.
"The win in the PGA Seniors has given me confidence to go forward here, and it was a long time coming to win a four-round stroke play event in America," said Montgomerie.
"It was 22 years since I first came over here at Pebble Beach in 1992. It's given me a great deal more confidence in the ability to know that you've done it once so you can do it again.
"I'm really enjoying my time here on the Champions Tour, and these major events are no different. I think if you're enjoying something, you're really quite good at it."
Whether or not his one-shot lead holds up by the end of the opening round at Oak Tree National, Montgomerie knows he will face a daunting task over the next three days when temperatures are expected to climb above 100 degrees Fahrenheit (37.8 Celsius).
"It's going to be difficult, no denying," said the Scot, who won a record eight European Tour order of merit titles. "But at the same time the rewards are great enough to warrant that, so I look forward to it." (Reporting by Mark Lamport-Stokes in Los Angeles; Editing by Frank Pingue)