Fritz wins delayed match to reach Shanghai Masters third round
Resuming at 4-3 in the first set, Fritz defeated 161st-ranked Atmane 7-6(4), 7-6(5).
"I thought he played really well and if I wasn't on top of my game... I definitely could have lost that match," said Fritz.
"I just stayed with it, and played solid in a lot of the big moments."
Fritz will next face Japanese qualifier Yosuke Watanuki.
World number 10 Grigor Dimitrov also managed to finish a delayed match on Monday, beating Belgium's Zizou Bergs 6-3, 3-6, 6-2 and the Bulgarian will meet Australia's Alexei Popyrin in the third round.
"It's been very challenging the last couple of days," Dimitrov said.
"But we just have to make the most out of what we have."
American Frances Tiafoe ended Chinese hopes when he defeated Zhou Yi 6-2, 6-4.
"(Zhou) played a good match, obviously it seemed pretty one-sided, but the second set was very tough," said Tiafoe after beating the last home player remaining in the draw.
In the third round, Tiafoe will meet Russian Roman Safiullin, who he called a "super dark horse".
"He can beat a lot of guys... He's had an up-and-down season, but he's capable," said Tiafoe.
Nine second-round matches have been delayed or rescheduled because of rain at the weekend.
The bad weather continued on Monday, causing further havoc to the schedule with play suspended on outside courts.