PEBBLE BEACH, Calif. – Having won his U.S. Open at Pebble Beach, Graeme McDowell knows exactly how demanding the layout can be. What he didn’t expect on Friday was a birdie run that put him into contention.

Following two bogeys through his first three holes, McDowell converted from 8 feet for birdie at No. 4, 15 feet at No. 5, 4 feet at No. 6, and 9 feet at No. 7.

“You make four straight, you don't feel you should do that at a U.S. Open. I saw the stats yesterday. It looked like it was close to three shots easier for Round 1 than it was in 2010,” said McDowell, who won the '10 U.S. Open at Pebble Beach.

The rest of his round, however, was pretty much exactly what he’s come to expect from Pebble Beach. Following another birdie at the 10th hole, he bogeyed the 11th and 14th holes for a 1-under 70 and a 3-under total that was six shots off the pace.

After two days of relatively benign scoring conditions, McDowell predicted that the layout will continue to firm up over the weekend and become an increasingly difficult test.

“It hasn't shown its teeth yet,” he said. “You have to be careful what you wish for out here, because you could be out there tomorrow thinking there's the teeth and I don't really like them anymore.”