Cape Town - Lance Stroll has said it is "shocking" to see how much of a backwards step Williams have taken at the start of the 2018 season.
After just two races, Williams are the only team left not to score a single point in the World Constructors' Championship, with their FW41 way off the pace in all areas.
More evidence of Williams downfall was compiled at the Bahrain Grand Prix last weekend, where Stroll's best time in qualifying was four tenths down on his lap in 2017.
And Stroll has said that there is a long road ahead for Williams for them to get involved in the midfield fight.
“There’s a lot of things to address, we’re far from where we want to be. There’s a lot to address for sure,” Stroll said.
“In Bahrain it was shocking how much of a step backwards [we made] - four-tenths slower than I was last year.
“We were losing time on the straights. We haven’t improved. We improved a bit in the corners, but not even close to the extent we were hoping four.
“But then in Australia we improved the lap time a little bit compared to last year when Felipe [Massa] was in Q3. It’s a bit up and down, but it’s still early days.
“There’s still 19 races to go, and there’s a lot more to understand and to look at before we come to a conclusion.”