Jason Day’s injury curse has resurfaced at a terrible time, casting a cloud over his fitness just two weeks out from the Masters.

World No.2 Day suffered a back injury during his opening round 3 and 2 win over Graeme McDowell at the World Golf Championships Match Play in Texas.

The 28-year-old Australian was three-up after 14 holes when he winced in agony hitting a tee shot on the 15th hole, straining something in his lower back and suffering shooting pain.

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He was able to scratch out halves in the next two holes to win the match but was in serious discomfort, struggling to walk.

“It’s really hard to play with searing pain in both sides of your lower back,” Day told AAP between the 15th and 16th holes.

He was hustled straight from his victory at the 16th green to get treatment and emerged about an hour later with painkillers, before being ushered away from the course.

While still struggling to walk freely, he was more optimistic.

“I’m struggling but I feel a lot better than I did an hour ago,” he said.

With fears he may withdraw and with his Masters tilt under a cloud, Day’s agent Bud Martin issued a statement, saying Day had “tweaked his back” but would likely return to play his next match against Thongchai Jaidee on Thursday afternoon.

Day’s brilliant career has frequently been interrupted by injury and illness.

Over the last five years, he has missed tournaments through back, ankle, wrist and thumb injuries as well as others with illness and vertigo.

So he will have his fingers crossed that he can return to the Masters and chase a second straight major championship title to back up his US PGA Championship breakthrough late last year.

The Masters is a title Day dearly covets after going extremely close to winning at Augusta National twice before – and also having battled injury there.

Day’s countryman, world No.6 Adam Scott gave up a golden chance to win his first match at the WGC-Match Play since 2010, losing two of his last three holes to halve with Belgium’s 55th seeded Thomas Pieters.

“It’s pathetic honestly. Poor play the last couple of holes and you can’t win a match like that,” Scott said.

“You have got to close it out like you’re trying to win a tournament and that wasn’t good enough today.”

Another Aussie, Marc Leishman, also rued his finish when he bogeyed the final hole and had to settle for a halved match with American Ryan Moore.

Their destiny remains in their hands as wins in their remaining group matches would see a worst case scenario of a playoff for a spot in the knockout stage.

Matt Jones had a one-up lead through 12 holes over South African former British Open winner Louis Oosthuizen but lost three of the next five holes to be beaten 2 and 1.

World No.1 Jordan Spieth won 3 and 2 against Jamie Donaldson and No.3 Rory McIlroy benefited from a late shank from 64th seed Thorbjorn Olesen to win 1 up.

– AAP