Villa are said to value the Argentine at around £40 million ($54m), which may be beyond the Red Devils' price range. United, on the other hand, have turned to Martinez as first-choice keeper Andre Onana is said to be ruled out for the start of the new Premier League season due to a torn hamstring. Doubts remain about whether the Cameroon international is up to the task at United after two mistake-ridden seasons but Martinez may not be the answer, either.