Nico Rosberg heads Lewis Hamilton in final Brazilian Grand Prix practice
Nico Rosberg headed team-mate Lewis Hamilton in final practice at the Brazilian Grand Prix as their title fight reaches a critical stage.
Rosberg, who is 19 points ahead, will be world champion if he wins Sunday's race and was 0.093 seconds quicker than Hamilton as they prepared for qualifying.
The session was held on a dry track but with a persistent misty drizzle, and further rain is predicted for qualifying from 16:00 GMT.
Ferrari's Sebastian Vettel was third quickest, 0.219secs off the pace.
The German baet team-mate Kimi Raikkonen and the Red Bulls of Max Verstappen and Daniel Ricciardo, with only 0.5secs separating the top six.
Qualifying for the race will be live on the BBC Sport website from 16:00 GMT and on 5 live at 16:30.
Hamilton knows he effectively needs to win the race to keep the title fight alive until the final race in Abu Dhabi in two weeks' time.
The world champion had looked in control throughout Friday practice but Rosberg had the edge on Saturday morning in much cooler conditions.
Hamilton was losing time into Turn One and Turn Nine and will be desperate to take pole and hope to control the race from there.
However, the weather is predicated to change again for race day, with heavier and more persistent rain expected in Sao Paulo, where forecasting is a notoriously difficult task.
Behind the top three teams, Williams' Valtteri Bottas was seventh, split from team-mate Felipe Massa by Renault's Jolyon Palmer.
McLaren's Fernando Alonso was 10th despite losing much of second practice on Friday with a hybrid system problem.
The Spaniard was 0.748secs quicker than team-mate Jenson Button, who complained he was struggling with the balance of his car.