The British number four won the first set in stifling conditions in Paris, but wilted thereafter in a 5-7 6-4 6-3 6-1 defeat against his Spanish opponent.
Things went wrong before the match for Evans, who was caught out by a retirement in the preceding contest on Court 2, resulting in him eating too close to going on court.
After five games he told coach Mark Hilton agitatedly that he could not breathe and, although he won the first set impressively, he was then ill off court."I just threw up a little bit," said the 27-year-old.
"It was just sitting in my stomach, so I thought it was the best thing to do."I actually came out and played pretty good at the start of the second.
"But it's difficult. I find it especially difficult on my serve on this surface to get on top in the rallies. It was hot. It was really tough. It was difficult conditions especially for such a physical surface for me.
"I didn't feel good at all. It's not an excuse, but it's just how it was."
Robredo is 35 and ranked down at 271 after injury problems in recent years, but remains a tough customer on clay.
Evans had not played a match on the surface for nearly three years before this season, so certain was he that he could not make it work for his game style.
He picked up his first two ATP Tour wins on clay in Barcelona last month, but has surely been counting down the days until he can set foot on grass.
That will be very soon - he has doubles here with Kyle Edmund first - after a performance against veteran Robredo that showed both how far he has come on clay and how far he still has to go.
There were noticeable improvements in his movement and his groundstrokes, particularly his single-handed topspin backhand, from which flowed several scintillating winners.
Had Evans held on to an early advantage in the second set, things might have turned out differently, but a poor game at 2-1 gave Robredo some momentum and he never relinquished it.
Evans said of Robredo: "Obviously he's been struggling a little bit. I think he just didn't find his feet at the start.
"And then it was clear he was way better than me on that surface and looked physically better as well, which was a bit worrying."
The Birmingham player is confident he is in good shape for the grass-court season, though, and hopes he will benefit from his clay travails.
"I feel good," he said. "I've played a lot of tennis. It's a different story on the quicker surface. Obviously, the surface helps me a lot.
"I don't worry about five sets on the hard or the grass. It was just today was definitely a lot different to what I imagined."
