Mercedes has been forced to make a second set of power unit changes to Valtteri Bottas's car ahead of this weekend's Abu Dhabi Grand Prix after an issue emerged during practice on Friday evening.

Bottas retired from the last race in Brazil due to an engine failure that prompted Mercedes to introduce a new one for the season finale, triggering a grid penalty for the Finnish driver.

Bottas had been due to start last on the grid after taking a fresh engine, turbocharger and MGU-H on Friday ahead of FP1, only for Mercedes to report a leak had been found in the closing stages of FP2 at the Yas Marina Circuit.

The team confirmed in the lead-up to final practice in Abu Dhabi that Bottas had taken another new engine, MGU-H and turbocharger, as well as an additional MGU-K.

While this adds up to a back of the grid penalty, it will have no bearing on Bottas's starting position given his existing sanction that had already demoted him.

No other power unit element changes have been made so far this weekend. Kimi Raikkonen, Daniil Kvyat and Sebastian Vettel will all run fresh gearboxes in this event, doing so without any penalties applied.

Bottas set the pace through Friday's running in Abu Dhabi, but refused to look too much into the times given his penalty.

"From today it looks positive. You always need to be careful because it’s only practice and you see many teams normally make big jumps into Saturday," Bottas said.

"The main thing for me and to focus on in FP3 is to try and get a good car for the race pace because no matter what I do in the qualifying I will be starting last. That’s the reality this weekend, so I need to focus on the race pace."