Well, this isn’t ideal two weeks out from The Masters.

Jason Day was cruising along at 3-up over Graeme McDowell when he informed caddie Colin Swatton on the 15th tee that something was wrong.

“He grabbed his back and said, ‘Oh, I just tweaked it,’” Swatton said outside the clubhouse after Day limped in to an impressive 3-up win in the WGC-Dell Match Play Championship.

Day dropped his driver upon finishing an aggressive 16th tee swing, leaving Swatton to pick the club up as the world No. 2 clutched his lower back in obvious pain. Day, who won last week’s Arnold Palmer Invitational, gingerly strode down the fairway before attempting to walk down a steep, 12-foot deep bunker face. He avoided further injury and carded a match-ending par.

Day’s condition was unknown after leaving the property to receive further treatment. The US PGA Tour’s on-site staff said he would have no comment.

McDowell was understandably frustrated with his own play after a strong start.

“I’m not going to say it rubbed salt in my wound when a guy is 3 up with three to go. And then he starts hurting and is able to limp up and win the match. But it does put a salty edge in it for me.”

Not that McDowell was rooting for his opponent to suffer.

“You never wish an injury on a guy, especially on a guy on top of his form like Jason is, and as good of an athlete as Jason is.”

Day could concede his second day match to Thongchai Jaidee, and return Friday for his date with Paul Casey.