Dan Carter believes England's selection strategy could harm Owen Farrell's chances of wearing the No 10 jersey during June's Lions tour.
The World Cup-winning All Black claims Farrell should be Warren Gatland's first-choice first five-eighth in New Zealand but fears he may not get a fair trial.
With stiff competition from Ireland's Johnny Sexton, Carter says Farrell's prospects would be boosted if Eddie Jones stopped picking him at centre.
"Owen Farrell's been in fantastic form for a year or two and he would be my pick at fly-half," said Carter. "He's worked out a good partnership with George Ford for England.
"Warren Gatland's been pretty open that selection will come down to form and the Six Nations is the perfect platform. But you could question the fact Farrell's been playing 12 for England. That might work against him."
Despite starting at No 10 for England, Farrell's midfield partner, Ford, is not being tipped as a Lions starter.
He is unsettled at Bath and Leicester coach Aaron Mauger - a former team-mate of Carter - refused to rule out a move for the playmaker on Wednesday night after Owen Williams secured a £300,000 switch to Gloucester.
"We would like to have kept Williams,' said Mauger. "We haven't spoken to George at all and as far as I'm aware he's still contracted to Bath, so I'm not sure if it's possible.
"If he was available it's potentially something we'd look at. George came through the academy here. He has ties here but we'd still look at him even if he didn't."
As well as playing alongside Mauger for New Zealand and the Crusaders, Carter was also coached by the 36-year-old before he moved to Racing 92 in 2015.
Racing face Leicester on Sunday - Mauger's second game since taking over from Richard Cockerill - and Carter believes his countryman could be a perfect mentor for Ford.
"Even when we were playing Aaron was basically coaching the team," said Carter. "It was quite bizarre to have a 24-year-old taking charge and I knew he'd make a coach one day."