Shane Williams believes Munster can cause Biarritz major problems as they bid to reach the May final at Paris's Stade de France.
Williams said: "Munster will have watched our game closely and they will realise Biarritz are beatable.
"Anything can happen in the Heineken Cup but we have shown that you can score tries against Biarritz.
"We all know what kind of team Munster are and they will have to take their chances.
"They can't afford to give away penalties or concede possession to the likes of Yachvili and Damien Traille. They are top class players."
Biarritz centre Traille opened the scoring inside 29 seconds with the first of three drop goals to set the tone for a pulsating encounter in the Basque country.
Then Takudzwa Ngwenya produced a moment of magic on 12 minutes to give Munster wings Doug Howlett and Ian Dowling sleepless nights.
The USA wing sensation picked up the ball inside his 22 and scored a superb 80-metre solo effort by brushing aside Mike Phillips and then Williams with an electrifying turn of speed.
Williams said: "It was disappointing because it was a poor attempt at a tackle by me. But he took his try well.
"He's a good player who got recognized after a great World Cup in 2007 and is one of the quickest around."
The Ospreys rallied through a rare score by Ryan Jones and Lee Byrne also crossed but Biarritz held a slender 16-15 interval lead.
Dan Biggar nudged the visitors ahead before Yachvili restored the advantage for the hosts with a penalty before full-back Iain Balshaw touched down.
Ospreys replacement Nikki Walker set up a grandstand finish with six minutes remaining but Biarritz closed the game out as John Isaac's men bid for European glory.
Isaac said: "We are delighted with the result. It was a close game but I thought we were full value for our win.
"It was difficult for me on the touch-line near the end but we held out. Roll on the semi-finals."
