Nico Rosberg fears an ageing engine inside his Mercedes will give team-mate Lewis Hamilton the upper hand at this weekend's Abu Dhabi Grand Prix.

The duo again led the way during practice at the Yas Marina circuit on Friday, with Rosberg setting the fastest time of the day in P2 as he finished 0.138 seconds clear of Hamilton.

He does not expect that speed to stay through qualifying and the race, though, due to his car having an older engine than the world champion's.

"It's a good start to the weekend," he said. "And even though Lewis has been showing his pace on one lap and in general, it's going to be difficult because I have an extremely old engine, having lost my fourth engine, so I have a lot of miles on it and that's costing me straight-line speed. 

"It's very, very high mileage because it's a very old engine.

"This track is an engine track and it was already difficult in Brazil and the race before that, but now on the straights this is an engine track and it will cost me in lap time. It is what it is and I just have to make the most of it."

Meanwhile, Hamilton was not happy with his long-run pace after P2 and fears it could hamper him in Sunday's race.

"The long-run pace doesn't feel so good," said the three-time world champion. "So that is what we have got to work on. 

"I made some changes between P1 and P2 and it did make it a bit better, but we need to make some more for P3.

"The race pace doesn't feel very good at the moment but it always changes when I get to the actual race."