Pebble Beach, United States: Jordan Spieth, last year’s US PGA Tour Rookie of the Year, and fellow American Jimmy Walker shared the lead after the first two rounds of the Pebble Beach National Pro-Am.

On a chilly Friday along the California coastline, Spieth fired a four-under 67 at the Monterey Peninsula course while Walker shot a three-under 69 at Spyglass Hill to leave both at nine-under, even though Spieth was on 134 and Walker on 135.

The $6.6 million event features players on three different courses over the first three days before the finish at Pebble Beach, creating the odd situation where players are level under par despite different total-stroke scores.

American Hunter Mahan fired a 68 at Spyglass to seize second at eight-under with rookie Andrew Loupe, the first-round leader, falling to fourth at seven-under following a one-over par 73 at Pebble Beach, one shot in front of US countryman Richard Lee.

Rain on Thursday caused 40 players to have to finish their first round on Friday, delaying the start of round two by an hour but not enough to prevent it from being completed.

Spieth began on the 10th tee and birdied three of his first four holes, then made up for bogeys at 18 and four with birdies on the second and par-five sixth holes before closing with a birdie at the ninth.

Spieth, who plays Pebble Beach on Saturday, enjoyed the structure of the event, where amateurs join the professionals.

“It’s cool to have a team event,” he said. “We don’t have them very often. I love any opportunity you get to have a teammate.”

Walker, who has already won twice since the current season began last October, began on the back nine as well, notching a birdie at 16, then another at the par-three third and a final one at the par-five seventh.

“I seem to play well out here,” said Walker, who on Saturday plays at Monterey. “A lot of times, pars are really good. You’ve got to stay real patient. I was tested really early today. I hit some poor shots and I did some serious scrambling.”

Walker won last year’s Frys.com event and last month’s Sony Open in Hawaii.

Four-time Pebble Beach winner Phil Mickelson fired a one-over 73 to finish level for 17th at four-under par.