On an extremely windy afternoon at Austin Country Club with gusts of up to 35 miles per hour (56 kph), Johnson coped manfully with the elements to beat German Martin Kaymer 3&2 .
"Putting is the hardest part," Johnson told Golf Channel after improving to 2-0-0 overall with his second straight win over a major champion. "It’s very breezy and then really gusty at times."
Despite two wins from two matches, Johnson was not guaranteed of advancing out of the group stage. He must win or halve his Friday match against compatriot Jimmy Walker to be certain of advancing to the final 16.
The format divides the 64 players into 16 four-man groups, with the winner of each group entering the knockout stage on Saturday.
After losing to Dane Soren Kjeldsen on Wednesday, McIlroy got a win on Thursday when his scheduled opponent Gary Woodland withdrew, citing personal family reasons.
Even with that walkover, however, McIlroy still needed Kjeldsen to lose his second match to have any chance of advancing out of the round-robin group stage.
But Kjeldsen duly shut the door on the Northern Irishman, beating Argentine Emiliano Grillo 4&3 on Thursday to improve to 2-0-0.
Kjeldsen said he relished the tough conditions.
