Former Formula One team owner Giancarlo Minardi would be disappointed if experiments on Lewis Hamilton's car by Mercedes were responsible for its reliability issues.
Electrical problems stopped Hamilton posting a qualifying time at the Chinese Grand Prix, forcing him to start from the back of the grid.
Mercedes were unable to shake those issues in Russia, with Hamilton qualifying 10th when he failed to post a time during Q3, though he recovered to finish second on race day.
And Minardi - founder of the team in his own name that went on to become Toro Rosso - would feel let down if the defending champion's struggles were the fault of tests by his team.
He told Omnisport: "F1 is made of cycles. I would be sorry if Mercedes would be doing experiments on the car, affecting its reliability."
Hamilton's team-mate Nico Rosberg has won each of the first four races this season and the last seven in a row, and Minardi is anticipating an interesting battle between the Mercedes duo in 2016.
"I really like Rosberg, I hope he will continue this streak. The season still has a long way to go and we will have to wait for F1 to be back in Europe to understand the situation a bit more," he said.
"It is an interesting battle between a guy who has never been considered as he should have been and a three-time world champion."
Ferrari have had a presence on the podium at each race in 2016, but the Italian believes Mercedes will not be caught.
"Ferrari made steps forward but must compete with an unbeatable Mercedes," added Minardi.
"Reliability will be crucial, because it is not possible to progress with no reliability. But this is a risk you come across when you cannot do private tests."