John Isner has come back from losing the first two sets at a Grand Slam tournament only twice in his career.
The first time was at the 2013 French Open, when he prevailed, 5-7, 6-7(7), 6-3, 6-1, 8-6, against his fellow American Ryan Harrison, then 21.
On Monday, in the first round of the United States Open, Isner, 31, again found himself down two sets to none against a next-generation American.
This time it was 18-year-old Frances Tiafoe, who served for the match in the fifth set before losing, 3-6, 4-6, 7-6 (5), 6-2, 7-6 (3).