NEW YORK -- Perhaps the greatest server of all time, Ivo Karlovic set a new mark Tuesday.
The 21st-seeded Croatian swatted a US Open-record 61 aces in a 4-6, 7-6 (4), 6-7 (4), 7-6 (5), 7-5 win over Yen-Hsun Lu of Taiwan to reach the second round of the season's final major.
Karlovic's total smashed the previous record held by Richard Krajicek, who in 1999 hit 49 aces against Yevgeny Kafelnikov.
After the match, Karlovic said he wasn't aware that he was in the process of setting a record.
"I [just] knew there was a lot of aces," Karlovic said. "I was, like, hitting them easy. At one point, almost every serve was an ace."
He was talking specifically about the second set, in which he hit an astonishing 22 aces in 35 strokes.
"The adrenaline ... I was in it," he said. "As the match was getting on, I was getting better."
Not surprisingly, Karlovic won more than 90 percent of his first-serve points and was broken only once. Karlovic equaled his ace total by hitting 61 winners. Just as impressively, he committed only 10 unforced errors in the 3-hour, 46-minute match. Karlovic's performance increased his all-time ace total to 11,277, the most in ATP history and 1,146 more than second-place Goran Ivanisevic.
Like the Williams sisters, Karlovic has defied time. At 37, he is the second-oldest player in this year's US Open draw, behind the Czech Republic's Radek Stepanek, who is three months older.
Just three years ago, Karlovic's career appeared all but finished. His ranking had fallen outside the top 160, and he had gone five years without a single title. This year alone, he has two, after wins at Los Cabos and Newport.
On Thursday, Karlovic will face American Donald Young.