Gunnell, who missed all of last season with a serious injury and could only watch as America's Kim Batten wrested away both her world title and world record in Gothenburg, inflamed an Achilles tendon in Lausanne last month.
The gold medallist of Barcelona has admitted that she is not 100 per cent fit and that she will be running through pain in Atlanta, but she showed no signs of difficulties as she coasted through her heat.
Gunnell, who turns 30 today, was drawn in the unfavourable lane seven, and was not able to get her stride pattern entirely right as the American Tonja Buford-Bailey, one of her main medal rivals, led the field.
The Brighton runner was forced to chop her stride around the top bend but when she entered the home straight she opened up before easing home in 55.29 seconds to come in just behind the American.
Gunnell, who showed few signs of having been in a race, despite the intense humidity, was happy enough with her performance.
"There were no problems, I felt fine," she said. "I just wanted to stretch my legs out and get a race under my belt. I wanted to take it nice and easy, and I felt in control."
Batten won her heat in 54.22 seconds as all the main players kept their cards firmly against their chests, and she and Gunnell were joined in today's semi-final by Ireland's Susan Smith, third in her heat in 55.22 seconds behind Deon Hemmings of Jamaica.
Also safely through to the next stage on an overcast but still swelteringly sticky morning were the 110m hurdlers Colin Jackson, Tony Jarrett and Andy Tulloch.
Jackson, the 1993 world champion who was only seventh in Barcelona after damaging a rib cartilage in the second round, had his heat sewn up by the third hurdle as he won in a time quicker than that of the Gothenburg victor, Allen Johnson of Canada.
Jarrett was also an easy heat winner, with Andy Tulloch qualifying third behind Germany's Florian Schwartzhoff to join the other two in the second round.
"It was easy," Jackson said. "But I've still got to put my foot down on the gas pedal. It should be fast, though."
Tony Jarrett, Britain's other medal hope, also looked highly impressive as he eased his way into the quarter-finals with a winning time in his race of 13.47 seconds.
Johnson, who succeeded an injured Jackson as world champion last year and the Olympic title holder, Mark McKoy, both progressed.
Johnson clocked 13.66 when winning his heat, while McKoy, Jackson's training partner who won the title in Barcelona for Canada but has since taken up Austrian citizenship, was second in his race in 13.70.
Jackson added that he felt for Linford Christie after his team-mate's 100m title had gone in such miserable circumstances on Saturday night.
"I haven't really spoken to Linford, but I know he's very disappointed and it was so unfortunate," Jackson said. "But I have to concentrate on what Colin Jackson can do. I have to focus on myself."
A ruptured Achilles tendon was not going to stop the high hurdler Henry Andrade from fulfilling his dream of competing in the Olympics. The California- born Andrade, representing the tiny African island archipelego of Cape Verde, lined up for his heat yesterday with his ankle heavily strapped, hobbled for two paces and then limped off to the side of the track.
The 34-year-old, whose parents hail from Cape Verde, twice missed out on selection for the American team in Los Angeles and Barcelona. Eventually, he had to turn to a country which he has never visited to earn a place with an Olympic team.
"The Olympics for me haven't been all I hoped they would be. But it was good to be here." he said.Reuse content