Munster would be nervously looking over their shoulder if they lose in Galway, with a final fixture against Lions.
Nonetheless, Gavin Coombes remains confident in the bid to repeat their 2023 title triumph.
“We’re so tight and connected as a group that belief inside this building is huge,” said the back-row forward.
Cardiff aim to ensure Welsh interest in the knock-outs and are fuelled by narrowly missing out to rivals Scarlets last season, but face the top two sides in the final weeks.
“It’s really tough to do all the calculations about other teams but it’s still in our hands and we can control it,” said head coach Corniel van Zyl.
“So it’s back to the old cliche of this week being the most important and we will try to get as many points as we can.”
A late win at Scarlets kept the Bulls seventh and they finish on home soil against the Italian pair of Zebre and Benetton.
Maximum points would not only claim a play-off place but potentially the huge advantage of a home quarter-final at altitude in Pretoria.
Ulster have recovered from a horrendous 2024-25 when they finished 14th, but have wobbled with back-to-back URC losses.
The Challenge Cup finalists finish against the top two in Belfast with scrum-half Nathan Doak aiming to build on their rousing semi-final win against Exeter.
“We’ve lost a few league games at home,” he said. “The last two games at home are massive for us. We’ll not be taking the foot off the pedal at all.”