Jason Day: "I felt nauseous all day"

Jason Day battled his way to the top of the leaderboard at the US Open despite feeling "nauseous all day".

The Australian took a share of the lead going into the final day, despite suffering from vertigo for a second successive day at Chambers Bay.

"I didn't feel that great coming out early, I felt pretty groggy on the front nine just from the drugs that I had in my system, then kind of flushed that out on the back nine," said Day, according to Sky Sports News.

"But then the vertigo came back a little bit on the 13th tee box, and then I felt nauseous all day. I started shaking on the 16th tee box and then just tried to get it in, really."

Day's round of 68 leaves him tied at four-under-par with Americans Dustin Johnson and Jordan Spieth, as well as South Africa's Branden Grace.