According to the Italian sports daily Tuttosport, there is substance to the rumours linking Robert Kubica with Ferrari.

According to the Italian sports daily Tuttosport, there is substance to the rumours linking Robert Kubica with Ferrari.

The Turin-published newspaper believes Renault's Polish driver has signed some sort of document with the Maranello based team.

The report said the "option" on the 25-year-old's services for 2011 must be taken up by Ferrari by July 15 of this year -- between the British and German grands prix.

Kubica told reporters in Barcelona that he is concerned that Renault's closest rivals could catch up or pull away this weekend.

He admitted he was hoping to see "a bigger upgrade" for the R30 in Spain.

"Most of the teams are normally targeting a big upgrade for Barcelona and I hope just they don't bring three, four (tenths), half a second, to here.

"If they do we might be a bit more in trouble but we'll see," added Kubica.

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