Susie Wolff has admitted she is surprised and disappointed with Williams\' latest signing.Given Valtteri Bottas\' back issues in Australia, Wolff - the British team\'s 32-year-old test and occasional

Susie Wolff has admitted she is surprised and disappointed with Williams' latest signing.

Given Valtteri Bottas' back issues in Australia, Wolff - the British team's 32-year-old test and occasional Friday driver - might have expected to be nominated as the official reserve.

But media reports after Melbourne suggested it was actually the reserve driver for Williams' engine supplier Mercedes, Pascal Wehrlein, who was put on standby for Malaysia.

And then Adrian Sutil strolled through the Sepang paddock gates, dressed in Williams gear and having a seat fitting in Bottas' car, having been hurriedly signed up by the team.

"Having most recently raced during the 2014 season gives him excellent knowledge of the current generation of race car," team boss Sir Frank Williams said.

"If the need arose, he would be a solid pair of hands to race the FW37 and assist our 2015 campaign."

Sutil's appointment, however, came as a surprise to Susie Wolff.

She attends all the races, will drive on Friday mornings in Spain and Silverstone, and will test the FW37 in the post-race tests after Barcelona and Austria.

Not only that, Wolff has already driven the 2015 car, having opened Williams' running on the opening day of the Barcelona test just last month.

Regarding the Sutil news, then, she admitted: "Of course I'm disappointed. I think it was a surprise for all of us that we were not expecting," Wolff told the German broadcaster Sky.

"I respect the decision of the team," she added. "I think they wanted to have someone with more racing experience and they chose Sutil."

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