George Russell has suggested Mercedes "go back to the drawing board" after being left "helpless" during the Bahrain Grand Prix.
The Briton finished seventh in the opening race of the season, two positions down on team-mate Lewis Hamilton.
Red Bull dominated to finish 55secs ahead of Russell, with both Aston Martins and Carlos Sainz's Ferrari also ahead of the Sáo Paulo Grand Prix victor.
"We had a good battle at points but both of us were on the back foot and were helpless when you are lacking a couple of tenths compared to the cars around you," Russell told Sky Sports F1.
"You are trying your best to battle with them but you can't hold them up.
"I think Fernando and Lance were really strong, Carlos was maybe on a slightly more level playing field but it was just a really difficult race for us."
No regrets
On whether there were any regrets from his race, Russell replied: "I think probably making a better race start.
"Lewis and I were on a similar strategy and I think perhaps if I was ahead of him at the end of lap one I could have ended where he was just because of how things were.
"P5, P7, P6, we don't really mind and don't really care. We are here to fight for victories and we are a long way from that.
"We need to hit the drawing board and see where we go from here."