Holder Hunter Mahan led 2010 winner Ian Poulter by one after six holes of their Accenture Match Play Championship semi-final in Arizona on Sunday.
The American got up and down from a bunker on the long second, but needed two attempts to escape from another trap beside the fourth green.
Back to all square as a result, Poulter drove into sand down the difficult fifth and went from there into the desert waste. The resultant bogey left him one down again, while Mahan still had not trailed in any game since the opening round last year.
In the first match out, Mahan's Ryder Cup team-mate Matt Kuchar was one in front of Australian Jason Day after seven.
Kuchar bogeyed the second after failing to escape from a greenside bunker at the first time of asking, but with them both just short of the green on the fourth Day was the one who could not get up and down.
A semi-finalist two years ago, Kuchar then moved in front with a 15-foot birdie putt on the short sixth.