Day, who was tied with Zack Johnson atop the leaderboard after 18 holes, carded a 4-under 67 Saturday to end knotted with Snedeker at 12 under-par 130 at the event, which was delayed a day due to Hurricane Earl.
Moving into fifth place was Luke Donald, who also carded a 67 to end at 10-under-par 132.
Tiger Woods and Phil Mickelson each fired 6-under 65s at the TPC Boston course. Woods was tied for 29th at minus-5 while Mickelson ended tied for eighth at 8-under 134.
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