Championship leader Nico Rosberg has topped the times ahead of title rival and Mercedes team-mate Lewis Hamilton in the second free practice session for the Italian Grand Prix.

The German, who leads Hamilton by 29 points in the title race, clocked a best time of 1 minute 26.225 seconds early in the 90-minute session on Friday, long before Hamilton, hampered by electrical problems, entered the fray with only half-an-hour remaining.

Hamilton, keen to make up for lost time spent waiting for repairs to sensors that had prevented his team from starting his engine, was swiftly on the pace and finally clocked a lap that was only 0.061 adrift of Rosberg.

This was clear evidence of his pace on a day when he had shown masterful speed in the morning to top the opening practice times.

He was fastest in both of the first two lap sectors, but was held up by traffic in the third – enough to show he had the raw speed to be fastest if he had a trouble-free run.

Finn Kimi Raikkonen was one-tenth of a second down in third place in the leading Ferrari ahead of his team-mate Fernando Alonso.

Fast-improving Finn Valtteri Bottas was fifth for Williams, ahead of Britain’s Jenson Button in his McLaren, with defending four-time champion Sebastian Vettel of Germany showing improved form for Red Bull back at the circuit where he gained his maiden victory in 2008.

Denmark’s Kevin Magnussen was eighth in the second McLaren ahead of Brazilian Felipe Massa in the second Williams, with Australian Daniel Ricciardo, in the second Red Bull, taking 10th place in a session of improving times on a warm, if overcast afternoon.