Elsewhere, Australian Lleyton Hewitt returned from a six-week injury break to thrash France's Nicolas Mahut 6-4 6-2 6-4.
American Roddick was made to fight before emerging with a 6-1 6-7 (6-8) 6-3 win over France's Nicolas Mahut.
The balance of power now sits with Mahut because he seems physically fresher.
Just after 2110 BST, Mahut complained that he was having difficulty seeing the ball and the decision was taken to suspend play.
Then, of course, there was the 11-hour, five-minute circus act, performed over three days, by John Isner and Nicolas Mahut at Wimbledon in 2010.
Mahut, from France, had his first break points of the entire set at 50-50, but Isner, 25, dug deep into his reserves to save both.
The 6ft 9in American had match points himself at 10-9, two at 33-32 and another at 59-58, all of which Mahut managed to fend off.
There was no indication of the drama that was about to unfold when Isner and Mahut resumed on Tuesday afternoon locked at two sets all.
After his match against Dent had finished, Djokovic was asked about the Isner-Mahut contest and said all the players were watching it in the locker rooms.
The Grand Slam record for a men's match is 11 hours, 5 minutes, an epic battle between John Isner and French opponent Nicolas Mahut at Wimbledon last year.
Isner, best known for his marathon encounter with Nicolas Mahut at this year's Wimbledon, eventually triumphed 4-6 7-6 (11-9) 7-6 (9-7) and will face Roger Federer in round three.
Roddick, who been troubled by a shoulder injury this season, looked on his way to a straight-sets win but Mahut fought back to level the match in a tie-break.
But unlike his clash with Nicolas Mahut at Wimbledon 2010, Isner was beaten 6-7 (7-2) 6-4 6-4 3-6 18-16 in a grueling contest which lasted five hours and 41 minutes.
Isner, with 98, and Mahut (95) have also both smashed the previous record for the most aces, the 78 set by Ivo Karlovic in a Davis Cup tie in 2009.
Czech 29th seed Radek Stepanek crashed out 7-5 7-5 6-3 against French world No. 81 Nicolas Mahut, who will likely face Djokovic in round three if he overcomes Japan's Tatsuma Ito.
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Speaking of sports, you have probably already forgotten the names Nicolas Mahut and John Isner , but their feat of carrying on the longest pro tennis match in history will likely last forever.
While Isner was almost delirious, Mahut, 28 and ranked 148 in the world, looked remarkably fresh, perhaps boosted by the knowledge he had won a match with Britain's Alex Bogdanovic in qualifying 24-22 in the final set.
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