Rupeni was at the heart of Agen's stunning 32-26 Heineken Cup victory over Gloucester at Kinsholm last Saturday with Cherry and Whites coach Dean Ryan singing the prasies of the 26-year-old.
"Sometimes it is not difficult to assess the quality of an international player because virtually everything they do in a game stands out," said Ryan. "That was the case when Rupeni Caucaunibuca inspired Agen to their victory over Gloucester in the Heineken Cup."
"His performance contained everything you would expect from a world class player. He has pace, power, cutting edge and the ability to not only score tries but create them too."
"There is no question he is a wonderfully gifted individual. He might not be the dimensions of a normal winger but he is someone exceptionally difficult to stop when on form, and for Agen he was close to the complete package."
And the alarm bells are already ringing for 2005 British and Irish Lions and Leinster captain and centre Brian O'Driscoll, whose Irish province face Agen in back-to-back Heineken Cup matches next month.
"If there is one player in the Heineken Cup who worries everybody it's Rupeni "Caucau" - he is so powerful, unbelievably powerful, and he goes amazingly fast," said O'Driscoll.
"He is going to cause us problems - no doubts about that. Closing his space down to stop him playing will be a key to our defence aganist Agen."
But "Caucau" is not the only star turn in a Pacific Islanders squad, packed with the cream of the players from Fiji, Samoa and Tonga, coached by Pat Lam and lead by Simon Raiwalui, the former Newport captain now the skipper at Saracens.