Toto Wolff says Mercedes has made it a priority to try and sort Nico Rosberg's starts out after a run of poor launches.

Rosberg was very slow off the line in China, dropping back in the field after contact with Valtteri Bottas at Turn 1 and having to fight his way through to second place. In Barcelona he was again slow off the line and Bottas almost jumped him after a strong start from fourth, but more crucially the start prevented Rosberg from attacking team-mate Lewis Hamilton.

Wolff revealed after the race on Sunday that Mercedes has been working specifically with Rosberg to try and sort the issue and was disappointed to see it continuing.

"On the starts we have a problem on Nico's car," Wolff said. "It seems to be a problem related to the clutch. That is a special project of ours; we expected some improvement for Barcelona which didn't kick in as expected. We just need to sort it out for Monaco because that's crucial there and we discussed it in the debrief."

While Rosberg had issues at the start, Hamilton was complaining over the team radio about handling problems but proceeded to set fastest laps in response to Rosberg's pressure. Asked if Mercedes takes Hamilton's radio messages with a pinch of salt, Wolff said it is clear they are genuine.

"We take it absolutely seriously because what we did was engineer the car away from how he wanted the car to behave on Saturday. Friday he was very satisfied with the car and then Saturday from P3 onwards he said the car was not doing what he wanted it to do.

"I think you saw that in Q1 and Q2 he wasn't performing the way he was expecting himself to perform, and I guess he just took it at the end with a Hamilton lap."