Ronan O'Gara will have to plan without his first choice scrum-half for La Rochelle's Champions Cup final clash with Leinster in Marseille on Saturday week.
Tawera Kerr-Barlow fractured his left hand in last Sunday's semi-final victory over Racing 92 in Lens and has been ruled out of action for six weeks.
The Kiwi, 31, was instrumental in La Rochelle's semi-final win against Leinster last year, but his side went on to lose to Toulouse in the decider.
Kerr-Barlow hopes to make it back in time for the Top 14 final if La Rochelle, who are currently seventh in the standings, make it to the decider for the second year running.
"My hand is broken, it will take six weeks to heal," said Kerr-Barlow.
"It's a shame, it's bad but it's the life of a rugby player. If we go to the final of the Top 14, maybe I'll be available."
Arthur Retière replaced Kerr-Barlow when he was injured early in the second half last weekend, and O'Gara will choose between Retière and Thomas Berjon to wear the number 9 jersey against Leinster.
La Rochelle face a tough test against Stade Francais in the Top 14 this weekend, while Leinster intend to rest their frontliners for their final regular URC fixture of the season against Munster at the Aviva Stadium on Saturday.
