The real reason why Rory McIlroy has a patch on his forearm at US PGA

It says a lot about Rory McIlroy's opening round of the US PGA Championship when the biggest talking point on social media is what the Ulsterman has on his arm.

McIlroy, who carded a lacklustre level-par 70 to lie six strokes off the early pace set by Gary Woodland, was sporting a new accessory in the shape of an anti-inflammatory patch on his right forearm.

The two-time US PGA champion said he began feeling tightness in his forearm and discomfort in his right wrist during the WGC-Bridgestone Invitational last weekend. 

“Yeah it's a bit inflamed and a little tight but it’s fine,” said McIlroy, who explained he was only affected by his arm on one shot Thursday.  “Funny enough, it hurts the most with chipping because I sort of hold the angle a little bit.”

In case you were having a restless night and wanted specific details, McIlroy is wearing a Stamina Pro patch.

According to the company's website, "The patches are not designed to treat traumatic injury but are useful for inflammation, fatigue, and the kinds of tension and aches and pains that dedicated athletes tend to suffer from."

McIlroy's tee-to-green game was on point for much of the first round, missing just three greens and ranking first in driving distance (328 yards), but he took 33 putts (ranking him 98th in the field).

Tiger Woods was playing alongisde McIlroy and matched his level-par 70, one shot worse than defending champion Justin Thomas.

Rickie Fowler lies one stroke behind off the pace on 5-under, as the American bids to remove his 'best player never to win a major' tag this weekend.