Rahm, who recorded the best of the day 64, leads by just one over joint 36-hole leaders, Rory McIlroy and Tommy Fleetwood, with Jason Day another two shots back and alone in 4th position.
Day hit a wild drive at the 1st today and took bogey but consecutive birdies at the 4th and 5th had him back on track and although it took until the 15th to record his next birdie he would also two-putt the 16th for another and he was within striking distance of Rahm who had finished 40 minutes earlier.
An excellent 12-foot par-saving putt at the last could yet prove crucial in the final analysis tomorrow and completed his round of 68.
With tough weather conditions expected tomorrow, Day was asked how that may suit his prospects.
“Bud Martin, my agent, always tells me this: Every time there's tough conditions or a tough golf course, he always walks in and he goes, this is really good for you, and then I laugh and I say, it's easy sitting in the bloody player dining; you know what I mean?
“It's stressful; I'm out here losing my hair; it's tough. I mean, the harder the better? Yeah, I would like to think so, but just because it's kind of harder for the leaders to get away. It's a lot easier to come back when it's obviously tough conditions, so there has to be a lot of patience tomorrow, and that's not only for myself but for everyone because it's going to be frustrating out there tomorrow.
“I'm hitting it nicely. I feel like I'm driving the ball well and I'm hitting a lot of good quality iron shots. Unfortunately, I need to putt a little bit better. But there's a good opportunity there because I think if I can keep that level of play up with my driver and irons and improve or get back to the standard that I feel like with my putting, then I feel like I've got a really good chance of winning tomorrow.”
Given he had to walk away from last week’s event in Orlando then Day is delighted to be in the position he is.
“I was just trying to get upright and be able to swing,” said Day referring to the difficulties he faced last week before withdrawing at Bay Hill.
“So it's actually quite nice to have the opportunity be in contention tomorrow, have an opportunity to win, so I'm very blessed about that, and I think if I can walk away hopefully a champion tomorrow, then that's a good little comeback, especially with how I was feeling last week.”
Adam Scott moved his way through the field with an impressive outward nine of 32 and when he birdied the 16th he was within hoping distance (at least) of being able to chase down those ahead tomorrow but at the 18th his tee shot found the water and he did well to make bogey.
Scott is six shots behind the lead and will need something very special tomorrow and some help from those he is chasing if he is to have any chance but he continues to build on his recent form and is not completely without hope.
Cameron Smith was the only other Australian to make the cut but a round of 73 today has him in 62nd place.
Rahm, though, has shown once again what an amazing talent he is and with a newly adopted attitude on the golf course where he is taking greater ownership of the mistakes he is making he is becoming scaringly good.
“Like I said, last year was -- I've said it many times, it was a year of personal growth rather than golf game, said Rahm. “It's been a work in progress of many years to get to this point, and it's hard to do when you're playing highly competitive golf.
“It's very hard to do. So I can't attribute it to one thing because I worked on many, many things slowly, and this is what I called earlier a midterm of hopefully it's a very good final project.”
Saturday showed that the TPC Sawgrass gives with one hand and takes with the other – sometimes more so there are still many chances as the event heads into day four.
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