Ulster captain Rory Best was disappointed to leave the Stade Marcel Michelin empty-handed as their second-half fightback fell short at Clermont Auvergne.
The Top 14 front-runners moved six points clear at the top of Champions Cup pool five after a first-half double from Nick Abendanon and Isaiah Toeava's first-minute score gave Clermont a 21-0 lead at half-time.
France outside-half Camille Lopez earned the bonus point with an interception try after half-time, before Ulster fought back.
Tommy Bowe crossed twice to add to Franco van der Merwe's drive-over score, but a late penalty try ended hopes of a losing bonus point and secured a 38-19 triumph.
Ulster will now need to win both of their remaining matches against Bordeaux-Begles and Exeter to stand any chance of qualifying for the last eight.
Clermont's knockout place looks certain, as they moved eight points clear after a third victory in four matches.
And Best was disappointed to leave France with nothing after their valiant second-half effort.
He said: "The damage was done in the first half, we knew we had to come here and start well and keep the ball for long periods of time and frustrate them.
"We are massively disappointed to come away with nothing. We expected to win, we prepared well and we knew if we did the things we talked about all week, we had a good chance.
"But we didn't do that at the start and it's cost us a losing bonus point which we put ourselves in a great position to get.
"We conceded turnovers and weren't good enough at the breakdown, we knocked on and gave silly penalties away and when you give a top side like this access into the game, they are going to score tries.
"We'll have a look at this, we go back into the PRO12 next week but we will be looking to finish strong.
"It's out of our hands a little bit but if we finish strong we will have a good chance of qualifying. But we're disappointed with the first 45 minutes of that game."
Abendanon's first-half brace gave Clermont the springboard to seize control of pool five.
And the English flyer believes this could finally be Clermont's year after falling short on two occasions.
He said: "We say this could be the year every year, but as long as we keep working hard and keep bringing the intensity and physicality we showed today then why not.
"We know we have the squad to get to get to a final and I'm sure if we get there, then this can be our year."