Cape Town - Williams are adamant that Robert Kubica is not the only option for next season but did reveal he can through the Abu Dhabi test without any problems.
Kubica was in action for Williams on Tuesday and Wednesday, setting the team's fastest lap time on the hyper soft Pirellis.
However, his soft tyre time was in fact 1.3s slower than that set by Sergey Sirotkin.
"I'm not going to talk about speed," said Williams' tech chief Paddy Lowe. "It's a complicated topic.
"I'm sure you want me to give some answers about that but it's not something we are not going to discuss.
"It's a really complicated topic, performance and speed, so to read a timesheet is quite misleading, so I'm not going to talk about that.
"We haven't even analysed it for ourselves."
He did, however, reveal that Kubica came through the Abu Dhabi test without any physical issues.
"We wanted to see Robert as he hasn't driven a current car, or current tyres, so of course it was interesting to see how he got on with that," he said.
"No problems. He's absolutely fine. Good driving, no complaints, no issues. All went well."
Lowe, though, insists Kubica to Williams is not yet a done
deal as the team is still considering other options.
"We’ll take the decision at the time we are ready. When we have all the information and we are ready to declare it.
"The drivers we brought to this test doesn’t mean that it’s the drivers under consideration for racing next year.
"This was a tyre test, which is an opportunity to look at two different drivers as well as for Lance to look at the new tyres. That was the purpose.
"Of course it gives us more information about drivers, but it’s not setting a definition from the pool from which we will pick race drivers."