ABU DHABI (AFP) - Nico Rosberg hopes that the much-improved Williams team can throw him a world championship lifeline in Sunday's season-ending Abu Dhabi Grand Prix.

The 29-year-old German, who needs to out-score Mercedes team-mate and championship leader Lewis Hamilton by at least 18 points, knows that a victory in Sunday's 55-lap "double jeopardy" contest may not be enough.

Rosberg needs to win and then see Hamilton finish third or worse if he is to take the title.

The Mercedes team dominated Friday's two practice sessions with Hamilton fastest in both ahead of Rosberg.

"We need to wait and see because the Williams, for example, was actually looking pretty good at some points today," he said.

"Of course, I'm hoping they're closer.

"The car feels good and the pace advantage seems to be there, for sure, at the moment, which is not necessarily a good thing. I need some help from someone else, but (Valtteri) Bottas is looking quick at times so we need to see where he really is.

"It's gone ok - not perfect. I haven't managed to get all my laps together properly.

"But I'm optimistic because I'm sure I'm going to get it together for qualifying. I'll adjust some settings and fine-tune."