The New Zealand defender, 35, who joined QPR in the close-season has taken the captain's armband in the absence of Park Ji-sung, who has a knee injury.
"We're still waiting to see how Ryan is but we're hopeful," Redknapp told the club website (www.qpr.co.uk).
"The doctor will give me an update but if there's anyone who can play with an illness or injury it's Ryan. He's one of those lads that gives absolutely everything," he added.
QPR are currently bottom of the Premier League on goal difference and have won only one match all season. They host Liverpool, who are 10th in the table after an inconsistent start to the campaign. (Reporting by Stephen Eisenhammer; editing by Toby Davis)