Valtteri Bottas' hopes of holding his own against close rival Ferrari were foiled in todays China GP which the Williams driver finished down in a lackluster 10th place while team mate Felipe Massa ended up 6th.
Bottas' fifth place on the grid augured well for a good performance but in the end, the Williams' pace as it ran through its successive tyre strategies just declined.
"It was a disappointing race," lamented Bottas.
" I was blocked at the start because of the crash between the Ferraris and lost many positions. The beginning of the race was looking alright, the pace was pretty good on the soft tyres, but once I went on to the medium tyre the pace was not there and I was struggling with overall grip.
"We need to check and see if everything was alright with the car, but it was difficult out there today in the last stint."
Bottas admitted the Safety Car action, prompted by debris on the track, threw a spanner in the works with regard to Williams' strategies.
"Every plan was ruined because of the Safety Car. At the start I was a bit unlucky, because the crash of the Ferrari cost me quite a few places, but it was going OK until the last stint.
"Unfortunately it all changed for the last stint but I still don’t know why. With the medium compound tyres I just couldn’t keep up the pace and it got worst and worst, costing me a few places.
"We need to check why the car wasn’t so good with the Medium tyres on the last stint."