Williams performance chief Rob Smedley has admitted that the team need to work on their pitstops, following two errors in the Malaysian Grand Prix.

Valtteri Bottas and Felipe Massa both suffered from slow stops due to "procedural" problems, and Smedley has insisted that the pit crew sharpens up ahead of the next race in China.

He told reporters: "We have work to do. We have to improve the consistency of the pitstops as we had some good pitstops but then both cars had some slow pitstops. The positive thing is they were two problems which we haven't encountered before.

"One was getting the tyre blanket off during the double pitstop, so it's a procedural thing, we just didn't take the blanket off quick enough. The second one was with Felipe. The jack didn't engage properly on the rear crash structure so we didn't get the rear of the car off.

"We have got to go away and look at it and understand what has happened and tidy up and make sure it doesn't happen again."

Bottas finished fifth in the race, just ahead of Massa in sixth.