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Justin Tipuric is the front-runner to take over Warburton's No.7 jersey, the skipper having been ruled out with a dislocated shoulder sustained in the final RBS 6 Nations game against England.
But it is Tipuric's clubmate Lewis, 23, who could be in line for his Test debut according to Ospreys coach Gruff Rees.
"I think he has a fair shot," he said. "He's forced our hand this year through weight of performances and consistency.
"I have previously spoken about Alun Wyn Jones being an eight-out-of-ten performer.
"Sam has been similar. He started off as a strong defensive player for us but now he's developing his attacking game and is fitting our pattern comfortably.
"He's forced our hand in terms of playing him and Tipuric in the same team together."