Rory McIlroy and Jordan Spieth were both beaten in their opening matches at the WGC Dell Technologies Match Play in Austin on Wednesday.
Among the first seven pairs to tee off, the pair lost to Soren Kjeldsen (2&1) and Hideto Tanihara (4&2) respectively.
Kjeldsen made an early gain on McIlroy with a birdie at the first in Group Two and was two up on the Northern Irishman at the 10th.
McIlroy turned things around with the help of a mammoth drive at 12, delivering three birdies on the spin to edge in front of the Dane.
However, Kjeldsen hit back with gains on the 14th and 16th holes and landed within a foot of the flag from his drive at the 17th to close out the match.
For Spieth - playing in Group Five - the damage was done after the turn. One down to Tanihara following a birdie at the seventh, Spieth was unable to reel in the Japanese debutant, who wrapped up the win with two holes to spare.