Jason Day closed out Graeme McDowell, 3 and 2, at the World Golf Championships match-play event in Austin, Tex., and then sought treatment for a back problem. Day was preparing to play Thursday, his agent said.
Top-seeded Jordan Spieth outlasted Jamie Donaldson, 3 and 2. Rickie Fowler, the No. 5 seed, rallied from three down on the back nine to square his match on the 15th hole, only for Jason Dufner to win the next two holes in a 2-and-1 victory.
In the round-robin tournament, players who lose still have a chance to advance from their groups and reach the knockout stage.