Ireland head coach Joe Schmidt says Johnny Sexton will be fit to face Samoa despite playing just one half of the win against Russia.
Ireland lacked fluency in an unconvincing win over Russia, but responded to their loss to Japan by claiming maximum points.
Robbie Henshaw is yet to feature for Ireland at the 2019 Rugby World Cup and Joe Schmidt remains reluctant to risk him against Russia.
Only four players remain from Ireland's stunning defeat to Japan, as Johnny Sexton captains his country for the first time against Russia.
Russia were beaten 34-9 by Samoa in Pool A, but captain Vasily Artemyev has no doubt they belong at the Rugby World Cup.
Samoa went down to 13 men during the first half, but Russia failed to capitalise before Steve Jackson's side cruised to a bonus-point win.
With captain Jack Lam injured, Samoa coach Vaeluaga Steve Jackson has called on Chris Vui to lead his side in their Rugby World Cup opener.
Jamie Joseph believes Japan struggled to deal with the weight of expectation in their nervy Rugby World Cup win against Russia.
Japan recovered from a rough start on Friday to begin their home Rugby World Cup campaign with victory over Russia in Tokyo.
New Zealand are favourites, but could they be toppled in Japan? We assess their major challengers for the Rugby World Cup.