– Sartorially, Jordan Spieth usually favors bright hues, but on Wednesday, the eve of the 99th PGA Championship, he wore a black cap and matching shirt.

"Just changing things up," he said.

When you're golf's darling and on the cusp of history, you wear whatever you please, without any sense of doom. No, the only gloom at Quail Hollow is the weather forecast, but has Spieth ever been deterred by rain or any other obstacle?

Yes, Spieth has a chance to achieve momentous things, namely becoming the sixth male golfer to complete the career Grand Slam and the youngest to do so. But on Wednesday he seemed serene, not antsy; introspective, not consumed.

"Expectations, I really don't feel any," he said. "This whole, 'This is a chance to complete the career Grand Slam'; I'm here, so I'm going to go ahead and try. But I believe I'm going to have plenty of chances. And I'm young enough to believe in my abilities that it will happen at some point.

"Do I have to be the youngest? No, I don't feel that kind of pressure. Would it be really cool? Absolutely."

Tiger Woods was 24 years and 6 months old when he became the youngest and most recent Grand Slam fraternity member, by winning the 2000 British Open at St. Andrews.

If this PGA Championship concludes Sunday, which judging from the weather forecasts might not happen, Spieth would be 24 years and 17 days.

Of the five players who have completed the Slam — Gene Sarazen, Ben Hogan, Jack Nicklaus and Gary Player being the others — none needed more than three attempts to win the final major.

It was just 18 days ago that Spieth seized his third Grand Slam leg by winning the British Open at Royal Birkdale. He's one of three active players who have won three legs of the Slam. The next three majors will afford each of those players a chance to complete the Slam.

Phil Mickelson, 47, lacks only the U.S. Open. He's finished second in that major six times, but in the three U.S. Opens he's played since attaining the third leg of the Slam (at the 2013 British) he hasn't finished closer than 15 shots out of the lead.

Rory McIlroy, 28, attained leg three of the Slam when he won the 2014 PGA Championship. Lacking only the Masters, he has posted top-10 finishes in all three ensuing attempts to finish the Slam.

The main difference between Spieth this week and McIlroy's first try to finish the Slam is that the 2015 Masters occurred eight months after his 2014 PGA win.

"It's a very long time and it plays on your mind a little bit," McIlroy said. "I think that's where Jordan doesn't have to deal with that coming into this week.

"It's great to be able to ride on the crest of a wave and just sort of keep it going."

Although Spieth won February's AT&T Pebble Beach Pro-Am by four shots and tied for second at the Dean & DeLuca Invitational at Colonial in late May, this wave he's currently riding didn't swell until he won late June's Travelers Championship by sinking a playoff-hole bunker shot.

Four months ago, when he missed the cut at his hometown AT&T Byron Nelson, Spieth faced questions about his erratic putting. Now he's on such a roll that comparisons are being made to 2015, when he won the Masters and U.S. Open, plus three other PGA Tour victories and the FedEx Cup title.

"I feel like around the greens and on the greens, I was stronger in 2015," he said. "But I feel like my ball-striking, especially my iron play, is better now than it was then."

Though weather was a factor at Royal Birkdale, Quail Hollow will present a different challenge because the expected rain will make the course play even longer than its listed 7,600 yards.

Whereas Spieth hit 290-yard drives with 20-plus-yard rollouts at Birkdale, there is little roll on Quail Hollow's already wet fairways. But the greens, with a SubAir system drying them, are firm and grainy.

"So you can land the ball within three paces of each other and end up 40 feet apart," Spieth said. "You have to have unbelievable distance control out here to get the ball close to these pins."

Spieth also described the thick Bermuda rough as brutal, not that he is daunted.

"The golf course is extremely challenging," he said. "I don't think it puts me at a disadvantage in any way to say that. That's what I'm playing against. But the biggest challenge is going to be the incredible talent that's out here this week."

TNT and CBS are all but openly rooting for Spieth to be in contention. With apologies to McIlroy, No. 1-ranked Dustin Johnson and other elite players, Spieth has emerged as golf's best hope of climbing out of its post-Tiger Woods-era TV ratings doldrums.

"I'm not sure the fringe fan, or even the media that doesn't cover golf on a regular basis, realizes that golf could be on the precipice of one of the greatest achievements in the history of the sport," CBS golf anchor Jim Nantz said. "And it's a responsibility we're really happy to have in our hands."

If Spieth feels burdened by this opportunity to make history and what it would mean for golf, he hasn't shown it this week.