He played the next two points, falling behind 3-0 in the second set, before taking a medical timeout to treat his hamstring.
Still, Roddick played on. Clearly restricted, he didn’t bother to chase down some shots and walked slowly between points with his head down.
Finally, after 16 more games, Roddick called it quits. He retired with Hewitt leading the second-round match 3-6, 6-3, 6-4.
“It’s a miserable, terrible thing being out there compromised like that,” Roddick said.
The 29-year-old American knew he wouldn’t be able to fool an opponent he was playing for the 14th time, one of the few players on the tour older than he is, somebody who was ranked No. 1 before he was and someone with one more Grand Slam title.
“He’s a tough guy to play,” said Roddick, now 7-7 against Hewitt for his career. “You can try to ham and egg it against a lot of guys. But he’s really intelligent. He knew what was going on.”
Hewitt, who turns 31 in February, goes to the third round against Milos Raonic, the big-serving, 21-year-old Canadian.
If Hewitt eliminates an opponent who has dropped only two service games this year, he could face defending champion Novak Djokovic in the fourth round. Djokovic, who won three of the four major titles last year, kept getting better in his 6-3, 6-2, 6-1 win over Santiago Giraldo.
Fourth-seeded Andy Murray, who lost to Djokovic in last year’s Australian final, ousted Edouard Roger-Vasselin, of France, 6-1, 6-4, 6-4. No. 5 David Ferrer beat American Ryan Sweeting 6-7 (4), 6-2, 3-6, 6-2, 6-3, and No. 6 Jo-Wilfried Tsonga downed Ricardo Mello, of Brazil, 7-5, 6-4, 6-4.
In today’s first match, Rafael Nadal stayed on track for his second Australian Open title and his 11th Grand Slam championship when he beat Lukas Lacko 6-2, 6-4, 6-2 in a third-round match.
Nadal, who strained his right knee last weekend while sitting down awkwardly at his hotel, again had the injured joint heavily wrapped but appeared not to be constrained during the match.
The first rally, won by Nadal on Lacko’s serve, lasted 28 hits, and the Spanish left-hander went on to break Lacko in the first game.