He leads by three shots from American Max Homa, with Denny McCarthy third.

Northern Ireland's Rory McIlroy, who was three shots off the lead after round one, carded a three-over-par 73 to drop to level par, 10 off the pace.

England's Tyrrell Hatton delivered one of the best scores on day two, carding four under to sit on that score in a tie for ninth.

Day, who lost his mother to cancer last year, said: "I lost a little bit of momentum with kind of my mum passing away and all that stuff."

The 34-year-old has been plagued by back problems in recent years and last won on the PGA Tour at this event in 2018.

"It's nice to be back in the mix, nice to be leading," he said.. "There are still two more days left, so I can't get too far ahead of myself."

Day - whose seven-under-par first round was his lowest opening score in six years - shot a three-under 67 on day two at a rain-swept TPC Potomac in Maryland, taking him to 10 under in all.

Despite putting himself in contention with a three-under-par opening round, defending champion McIlroy struggled.

He has won the event three times but made three bogeys on his opening nine holes on Friday and narrowly made the cut line.