March 22 Rory McIlroy and Jordan Spieth were among the early losers in Wednesday's opening day of the WGC-Dell Match Play as the two former world number one players suffered stunning upsets.
McIlroy, who reached last year's semi-final, fell 2&1 to Dane Soren Kjeldsen while Japan's Hideto Tanihara, making his first appearance at the tournament, beat Spieth 4&2 at the Austin Country Club.
Kjeldsen, who does not have a top-25 in any of his seven starts this year, stuck his tee shot at the par-three 17th to three feet and made the birdie putt to close out world number two McIlroy, who held a 1-up lead with five to play.
Northern Irishman McIlroy, who replaced Jason Day as world number two this week, will play Gary Woodland on Thursday and Argentine Emiliano Grillo on Friday. Woodland beat Grillo 3&2.
Twice major champion Spieth never led against Tanihara, who has 13 career titles overseas. The American played his last nine holes in three over and hit only one green to end his chances.
It marked the first time in four years that Spieth had lost his opening match.
Next up for the Texan is a clash with Japan's Yuta Ikeda on Thursday and Ryan Moore on Friday. Moore halved his match with Ikeda.
World number one Dustin Johnson was five up after nine holes against Webb Simpson while Japan's Hideki Matsuyama was all square through 15 holes with Jim Furyk.
Defending champion Day was one up after two holes against Pat Perez.
The event is comprised of 16 four-player groups who play round-robin matches from Wednesday through Friday with the winners of each group advancing to a single-elimination bracket at the weekend.
Players receive one point for a win and a half-point for a halved match that ends in a tie. (Reporting by Frank Pingue in Toronto; Editing by Clare Fallon)