A Jordan Spieth Grand Slam? In this crazy hot sports summer, why not?

The middle step on the medal podium now awaits young Jordan Spieth. The way things are going, is there anyone who dares to doubt what could happen?

For U.S. sports fans, these warm days of 2015 have been a joy ride. This has been the summer of our content, the days of wine and trophy poses.

Who knew what lay ahead when a former Mexico City bus driver named Victor Espinoza, having traded in his wheels for a whip, urged a horse named American Pharoah across the finish line first in the most important horse race in the world, the Kentucky Derby?

Who knew that Espinoza and his masterful trainer, Bob Baffert, would then team up to achieve what hadn’t been done in 37 years of thoroughbred racing? What was once somewhat routine but more recently viewed as impossible was right there in front of the watching world in the home stretch of the Belmont Stakes that first Saturday of June.

The roar that shook the ground and penetrated the sensibilities began as hope and quickly became joy. American Pharoah was in the lead, was not about to give it up, was going to win the Triple Crown!

And we’d only just begun.

Serena Williams won the Australian Open in January. Sadly, that tennis Grand Slam tournament is below our radar.

But for those paying attention, that was her second consecutive major title, and when she won again at the French, the buzz spread from tennis fans to ordinary sports fans. Let’s see, now. Wimbledon would be four in a row, wouldn’t it?

Holy cow.

But we were distracted by other spectacles.

Spieth, the yes-sir and yes-ma’am golf pro from Texas who had won the Masters in April, was in the hunt at the U.S. Open, an event played last month at Chambers Bay in Washington, where it seemed as if they flew in rocks and sand from the moon.

Didn’t bother Spieth. He played it smart on No. 18 on Sunday, knowing the guy behind him, Dustin Johnson, wouldn’t. His two-putt birdie, ignoring the more spectacular run at a eagle that was filled with danger, set up Johnson’s three-putt par from 12 feet and Spieth’s one-shot victory.

Spieth. Two majors in a row. Williams on the verge of four. This was really keeping sports editors hopping. Who gets the big headline?

Then the U.S. women’s soccer team answered that. They swaggered through the World Cup, beat Japan in the final, 5-2 — that’s like an 18-3 baseball game — and anointed several superstars. Carli Lloyd didn’t need to take off her jersey to get attention. She just scored three goals in the final.

Now, it was Williams’ time again.

She had somehow weathered a young Brit named Heather Watson, who was backed by a strangely ill-tempered Wimbledon Centre Court crowd. But she hung on to win that third-round match, and did so again in the final as another Centre Court crowd fell in love with a charismatic young Spaniard, Garbine Muguruza, who rallied, but never really had a chance to win.

This was getting to be a red-white-and-blue dream. Had we been handed weighted dice? Did every clover in our national sports field have four leaves?

The day after Williams won her fourth major tennis title in a row — the “Serena Slam” — that set her up for the ultimate run at a calendar-year Grand Slam at the U.S. Open in September in New York, Spieth was back at it.

He won the John Deere Classic again. In a playoff. Again.

And so, while Serena danced at Wimbledon’s champions dinner Sunday night, Spieth flew over and was here Monday, giving the Old Course a new look.

The British Open begins Thursday. And not just at some mowed field surrounded by tall grass and sprinkled with lots of sandy pock marks. At St. Andrews. Utter the words with reverence.

It’s Spieth’s turn now, his hot seat, on the biggest of golf stages. When the lights turn on here, the brightest ones will aim at him.

The usual stuff swirls around him. It comes with the territory.

Two-time major champion Martin Kaymer of Germany, apparently already having had his fill of all the Spieth hype, told the British media last week that Rory McIlroy — still ranked No. 1 in the world to Spieth’s No. 2 — was still the tour king, that he had excelled longer and deserved respect for that.

Last year’s European Ryder Cup captain, Paul McGinley, jabbed Spieth a bit, too, saying his playing the John Deere Classic was a mistake, that “95% of the players here have some links-course preparation,” meaning more than the few days before the tournament. Apparently, to McGinley, that’s more important than tuning up with a tournament victory.

It’s not lost on anybody that, were Spieth to win here, he could challenge for golf’s Grand Slam at the PGA Championship at Whistling Straits in August. They’d be dancing in the streets in Sheboygan.

For Spieth, who turns 22 on July 27, that is a huge order.

But this is the summer of 2015, a time when the extraordinary performers of our sports world keep separating themselves from the merely great.

So why not Jordan Spieth, one more time?

With feeling.

bill.dwyre@latimes.com

Twitter: @DwyreLATimes