World number one Jordan Spieth holed two crucial, knee-trembling putts on the final two holes to maintain the US team's slender one-point lead after Saturday's morning foursomes in the Presidents Cup.

Spieth, with partner Dustin Johnson, was up against the man he battled for supremacy in Majors all season, Jason Day, who was teamed with Charl Schwartzel.

Once again it was the young Texan who emerged victorious, as he had in the US Masters and US Open this year, while Day beat Spieth to win the US PGA Championship.

Spieth and Johnson were down from the fourth hole, three down at the turn and one down with two to play at the Jack Nicklaus Golf Club in Incheon, South Korea.

But nerveless Spieth rolled in a seven-footer for a birdie to square the match and then repeated the feat for a winning par at the 18th.