Damon Hill believes Williams should discard its current supply contract with Mercedes as it will never be in a position to battle for a world championship as long as it remains a client of the German manufacturer.
The former Williams driver and 1996 World Champion has acknowledged the Grove team's progress in the last couple of years but says that a move to the next level will only be possible if the team resorts to an alternate power unit supplier, such as Honda.
"I sort of suggested to Claire Williams last year that the problem is they have the same engine as the Mercedes team and that is always going to be a barrier between them winning a championship and Mercedes themselves winning a championship," Hill told Sky Sports.
"I think as a team wanting to win the outright championship strategically they would be better off with another engine and I think the only other engine you can think of is a Honda.
"I would have liked to have seen Williams opt to go with the Honda engine, I think Honda are going to fight back. They had an absolutely catastrophic year last year, but they learnt a lot.
"I could be wrong, but if they make the sort of impression they should, then for Williams to get ahead of Ferrari and Mercedes they are going to have to have a different engine to the Mercedes team."