SAN MATEO — Julian Nash measured his opening tee shot and ripped the ball down the fairway. The ball veered off course toward a eucalyptus tree, sending a pair of geese flapping madly for safety.

“Pretend the hole’s over there,” Nash said with a laugh. “Birdie!” a man shouted.

Nash is an avid golfer, but he was not playing golf on this windy spring afternoon. He was playing footgolf, an increasingly popular alternative that employs soccer balls and 21-inch cups.

The former professional soccer player stopped by Poplar Creek Golf Course in San Mateo earlier this month to inaugurate the Peninsula’s first 18-hole footgolf course, which runs alongside the traditional golf course and is 50 to 75 percent shorter, depending on a player’s ability.

Parshan Rayatkah, of Oakland, taps in his ball for a par on the first hole while playing in the Battle of the Bay Footgolf Tournament presented by the

Footgolf was born about a decade ago in the Netherlands and quickly spread to South America and the rest of Europe, said Harvey Silverman, an adviser for the American FootGolf League. The sport has now colonized the United States, where it’s made rapid gains in popularity.

“I think it’s remarkable, considering footgolf was only brought to the United States about four year ago and we now have around 475 courses,” said Silverman. “In 2015, we estimate that a million rounds of footgolf were played.”

Nash, who grew up in San Leandro and now resides in Burlingame, was introduced to footgolf a couple of years ago. He picked up the sport after playing a few years of Major League Soccer, including a brief stint with the San Jose Earthquakes.

He discovered it was a fun way to extend the life of his soccer skills while scratching his itch for competition. Nash has quickly become one of America’s best players, finishing high up the leaderboard in national and international tournaments.

“At the ripe old age of 33, things are starting to fall apart,” he said, “and this makes for a nice transition.”

Footgolf is also helping golf courses adapt to a changing sports landscape. Footgolf generated about $20 million in revenue in 2015, Silverman said, giving a shot in the arm to courses around the country that are struggling to cope with golf’s declining popularity.

Kevin Kobayashi is the general manager of Monarch Bay Golf Club in San Leandro, which established an 18-hole footgolf course two years ago.

“We’re a golf course first, so we didn’t want to displace any of our regular golfers,” said Kobayashi.

But the club also wanted to find a new generation of customers. Unlike the golf-obsessed baby-boom generation, Kobayashi said millennials tend not to spend their disposable income on club memberships and Big Bertha drivers.

Miguel Madruga tees off on the 3rd hole at the FootGolf course at Las Positas Golf Course in Livermore, Calif. on Thursday, Aug. 28, 2014. Madruga and

“We’re getting new customers that we never would have gotten,” said Kobayashi, who hopes some of those people eventually pick up golf as well.

There are five footgolf courses in the Bay Area. Poplar Creek is the only one that’s certified by the American FootGolf League, which makes the course eligible to host tournaments.

That could be a boon for the city-owned course, which is running an annual budget deficit of $450,000. Tim Heck, manager of Poplar Creek, doesn’t have dollar signs in his eyes yet.

“We’re kind of dipping our toe in the water as far as seeing if we can have golfers and footgolfers coexist — and so far it seems to be working out well,” he said a few days into the experiment.

There are, of course, broad similarities between the sports, from rules to mannerisms. Footgolfers study their putts before tapping the ball home. They toss blades of grass in the air to test the wind. And they often wear knee-length argyle socks as a gesture to golf’s tradition of preppy attire.

Chris Chirico, 29, was one of the first members of the public drop in for a round April 1. He saw a sign advertising footgolf and made a reservation right away. Poplar Creek offers footgolf everyday after 4 p.m.

“I want it to stay, so I’d better support it as soon as I can,” said Chirico, a soccer coach at Abbott Middle School in San Mateo. “I think it will complement a lot of the soccer clubs and programs that we have here in the San Mateo area.”

Contact Aaron Kinney at 650-348-4357. Follow him at Twitter.com/kinneytimes.