Thursday represents the start of the fourth event of the PGA Tour’s seven-week western swing, and easily the toughest challenge of the 2018-19 season.

After three-consecutive weeks playing courses that are considered scoring paradises, the Tour heads to the arduous Torrey Pines Golf Club for the most recent edition of the Farmers Insurance Open, an event that has had a winning score better than 10-under-par just once in the past five years.

The toughest stop of the early season has the strongest field so far as well – outside of October’s WGC event in China. Seven-time Farmers Insurance Open champion Tiger Woods headlines the field, as he does every time he tees up. In addition, world No. 1 Justin Rose will be teeing it up at Torrey Pines, as will 10 other players who currently rank inside the world’s top-17.

There are many intriguing storylines worth keeping a close eye on this week, but here are the four we like best:

1. Day Defends

Last year’s Farmers Insurance Open was so packed with drama that it needed an extra day. A thrilling final day had four players still in contention on the 72nd hole: Jason Day, Alex Noren, Ryan Palmer, and J.B. Holmes.

Holmes was the only one who ended up actually missing the ensuing playoff, but not before he probably lost himself a lot of fans with a bizarre display of questionable sportsmanship (he took a VERY long time to hit his approach shot, only to lay up anyway), and once the playoff started, Palmer bowed out on the first hole. That led to Day and Noren matching each other shot for shot for five extra holes, until darkness forced the continuation of the playoff into Monday morning.

The sixth playoff hole saw Day return to where he left off, carding an impressive birdie while Noren sent his approach into the water and made bogey.

The victory for Day was both surprising and unsurprising. Day had shown elite form before. He had won ten previous times on Tour, including one major (2015 PGA Championship), and spent 51 weeks as the No. 1 player in the world rankings. He had also played the Farmers Insurance Open tremendously before, also winning the 2015 edition and finishing runner-up in 2014.

That being said, he had not looked like the No. 1 in some time. His 2017 season was an enormous disappointment, as he banked just $3 million in earnings after having made more than $17 million over the previous two seasons. The victory at Torrey Pines signaled to the golf community that the former No. 1 was back.

Over the rest of the 2018 season, he looked varying degrees of “back”. He did post another victory, at the Wells Fargo Championship in May, and he finished co- runner-up to Ted Potter Jr the week after he won at Torrey Pines.

On the other side of that coin, Day had just five top 10s in 20 starts, and he failed to contend at any of the four majors. The U.S. Open was especially rough, as he opened with a 79 and missed the cut by a mile.

In the current season, Day has made three starts, finishing T5 at the CJ Cup, T11 at the WGC-HSBC Champions, and most recently, he finished 13th at the 32-man Sentry Tournament of Champions three weeks ago.

Now ranked 12th in the OWGR, how Day does in the 2019 season might depend on his irons. His short game is not just good, it is the best in the world: he finished 2nd on Tour in strokes gained: putting and strokes gained: around the green. Day has the length to compete everywhere, but in spite of all the darts he threw at the greens at Torrey Pines last year, he largely struggled with his irons, losing strokes to the field for the year, and finishing 124th in greens in regulation. It is a shotmaker’s tour, and Day fell short on that front last year.

2. Tiger in the Field

As the defending champion and two-time Farmers Insurance Open champion, Day will garner a great deal of attention this week. Day will not, however, be the most popular man in the field. That is because 79-time PGA Tour champion Tiger Woods decided to make Torrey Pines the location of his 2019 season debut.

Woods’ history at Torrey Pines absolutely dwarfs Jason Day, in addition to every other golfer who has ever teed up in La Jolla. Tiger has won the Farmers Insurance Open a mind-boggling SEVEN times, including four straight titles from 2005-2008. One of those victories (2008) was an eight-stroke romp. The course was also host when Tiger last won a major, the 2008 U.S. Open, where he famously took down Rocco Mediate in a 19-hole Monday playoff despite badly injuring his knee. There is no simpler way to put it: this is Tiger’s course.

By any objective measure, 2018 was an rousing success for Tiger Woods. After missing nearly two years of play after back fusion surgery, Tiger assimilated himself back to the Tour quickly, despite having to largely re-tool his swing to put his pressure on his troublesome back. He finished runner-up at the Valspar Championship in March, just his fourth event back, and followed that up with a fifth place finish at the Arnold Palmer Invitational the very next week. Different parts of his game eluded him at different times, mostly his driver early on, and then his putter around midseason, but by July, he was back to being a week-in, week-out contender. Among other highlights, he finished runner-up to Brooks Koepka at at the PGA Championship, and most notably, he captured his first victory in five years when he rode two rounds of 65 to a win at the season-ending Tour Championship. As a result, he ended up finishing second in the final FedExCup standings, a tremendous accomplishment after everything he had gone through. Over the course of the season, his world ranking rose from 656th all the way to his current position of 13th.

His stellar course history aside, there is reason to be a little skeptical of Tiger’s chances for an eight Farmers Insurance Open title this week. While his last official event was that impressive victory at East Lake, he struggled in the three events (none official PGA Tour event) he has played since.

He was absolute disaster at the Ryder Cup, posting an unthinkable 0-4 record for the losing American team. He then lost the much-publicized “The Match” against Phil Mickelson on Thanksgiving weekend. Most recently, he finished 17th out of 18 competitors at the Hero World Challenge, an event Tiger hosts in The Bahamas every year.

It is very possible that Tiger had just ran out of gas by the end of the year; he had played his busiest season in a long time. He has had time to rest since the Hero World Challenge was held in early December, and the entire sports world is going to be interested in how he performs when he makes his season debut this week.

3. Who is Adam Long?

Last Sunday, the entire golf world asked wanted to know one thing: who the heck is Adam Long?

Long, a 31-year-old Duke product had missed his last three cuts, and in five career PGA Tour cuts, he had four missed cuts and a T63. Yet, everything was able to come together for Long at last week’s Desert Classic, as he outdueled Hall of Famer Phil Mickelson and the much-higher regarded Adam Hadwin to take the title at La Quinta.

It was one of the most out-of-nowhere golf stories in recent years. The last time Long had won on ANY Tour was in a 2011 Hooter Tour event.

Long had been a Farmers Insurance Open alternate a week ago, but after his breakthrough victory at the Desert Classic, he is firmly in the field at Torrey Pines this week, paired with Tour vets Gary Woodland and Stewart Cink for the first two days.

Long now has a two-year PGA Tour exemption and will be making his first Masters start in April, but is it too much to expect his to be competitive this week? Maybe. More often than not, players experience a let-down in the week following their maiden Tour victory, and Long is suddenly dealing with more distractions than he likely thought possible. It does not help that he has never played this event.

Still, Long very much defied the odds last week. It would probably be unwise to doubt him again. If he putts at Torrey Pines the way he did at the La Quinta Stadium Course, he stands a good chance of at least making the weekend.

4. Hot Schauffele

Without a doubt, the hottest golfer in the world right now is Xander Schauffele. The 25-year-old former Tour Championship winner has won his last two official PGA Tour starts: the first at the WGC-HSBC Champions in China, and the second at the Sentry Tournament of Champions three weeks ago.

At the latter, Schauffele looked unstoppable in a Kapalua comeback effort where he shot a Sunday 62. His form is about as good as can be at the moment.

Following his 2017 PGA Tour Rookie of the Year campaign, Schauffele had an up-and-down 2018 season. He finished well down the leaderboard at a lot of the “regular” events, but he has developed a penchant for showing up big in the big events. He did not win on the season, but he took runner-up at both THE PLAYERS Championship and at the Open Championship, where played with Jordan Spieth in the final Sunday pairing. He was also T6 at the U.S. Open, and posted results of T3 and T7 at the final two FedExCup Playoff events, respectively.

Given that Schauffele is a La Jolla native and has presumably played Torrey Pines a plethora of times, his history in the Farmers Insurance Open has been surprisingly poor.

In the only Tour event that Schauffele has played thrice, he has gone missed cut, missed cut, missed cut. Maybe playing so close to home added additional pressure, but with his current form, it would be very surprising if the now-World No. 6 does not post, by far, his best event performance yet.