LOS ANGELES - World number one Jason Day powered through the fatigue lingering from last week's Masters campaign to seize a share of the halfway lead at the RBC Heritage. Australia's Day fired a two-under par 69 in challenging, windy conditions at Harbour Town Golf Links in Hilton Head, South Carolina. He shared the lead on six-under par 136 with Americans Charley Hoffman and Kevin Chappell, who both posted 68s. The top trio were one stroke in front of another three players that included overnight co-leader Luke Donald, who carded a 71, Scotland's Russell Knox (65) and American Patton Kizzire (68). Day said gusting winds on Friday made life difficult. "It would be 20 miles per hour and then suddenly die down," Day said. "Very, very tough day out there. I'm glad I got it in at two-under."