From the sublime to the nauseous. Rory McIlroy could not produce the brilliance of his opening-round 63 here in the second round but he manfully fought off the effects of a stomach upset to retain the lead in the Desert Classic.
The Ulsterman heads into the final two rounds a shot clear of the American Brooks Koepka on 11 under after a 70. McIlroy trudged in looking pale but also determined and confident.
"I expect to win from here," he said. " I know the course as well as anyone else and I expect to go out there and shoot two good scores and lift the trophy."
But then, McIlroy "expected" to compile a commanding halfway advantage with which to stroll to his first European Tour win in 15 months, having finished runner-up in Abu Dhabi a fortnight ago. While Koepka's 65 is one obvious factor why his cushion is the bare minimum, then so too was the dodgy takeaway McIlroy had consumed.
The 24 year-old awoke feeling queasy and required repeated trips to the lavatory and, although he refused to seek excuses for his somewhat pedestrian round of two under, his body language plainly was not right.
In the first round, playing partner Stephen Gallacher referred to McIlroy's nine-under performance as "sublime". The Scot's 66 had not been too shabby itself but yesterday mediocrity covered the marquee three-ball, with Gallacher only able to advance his score forward a stroke to seven under.
Tiger Woods was the other member and his 73 was scruffy to the point of ugliness. The world No1 hit only four fairways and, but for his legendary scrambling powers (he got up and down 13 times out of 14 attempts) he would have missed his second cut in as many weeks.
Woods employed some nifty golfing jargon to explain his tee travails. "I've been hitting hot pulls and every one of those things has some serious heat on it which is nice, but I just need to get it online," he said. "I would rather hit the hot pull than the big flame-out, crop-duster to the right ... because it's easy to fix. I need a lot of wind on the weekend and to play two great rounds."
Of course, Woods is capable of breaching the eight-shot deficit, yet it is not merely McIlroy he must overcome. Koepka should not be underestimated.
The 23 year-old took the Peter Uihlein route on turning professional in 2012, deciding to emulate his great friend and countryman by launching his career in Europe. The Floridian earned his full card last season courtesy of three wins on the Challenge Tour and then, in October, almost won on the PGA Tour at the Frys. Com Open in Scottsdale.
There are two back to a group on eight under, including the Yorkshireman Danny Willet, who shot a 65. And alongside Gallacher on seven under after a 67 is Henrik Stenson. The Swede has struggled at the start of this campaign since becoming the first golfer to win the Race to Dubai and the FedEx Cup last year, missing the cut in Abu Dhabi and finishing in a tie for 28th last week in Qatar.
But he feels the good days will soon return: "Today is the best I've putted in a long time," he said.