BBC Sport has reported:

George Russell says he will take another grid penalty later this Formula 1 season after an engine change forces him to start Sunday's Singapore Grand Prix from the back of the grid. The Mercedes driver said he needs a further new engine once an upgrade is ready, because seven races remain and his current engine allocation will not cover them all.

Drivers are permitted four engines in a season, Russell said, which works out to six races per engine this year. “You get (a limit of) four engines a season, so six races on each, and we have seven races to the end. So I will be taking another penalty, so yeah it's pretty relentless at the moment.”

Russell's engine failure in Malaysia disrupted Mercedes' earlier plan to keep his older engine in use until the upgrade was ready, most likely for the next round, the United States Grand Prix in Austin. He said Mercedes does not have the upgraded engine for Singapore, and there was no earlier-season engine available to use after the failure.

“I knew I was going to have penalty,” Russell said. “The plan was always to go in Austin, and obviously Singapore is the second hardest track to overtake on on the calendars. So you would never choose to do it (here).”

He said the team had no engine he could return to because of “all of the various failures.” With seven races left and no upgrade available this weekend, he said Mercedes could either hope an engine lasts the distance while accepting a performance loss as it degrades, or accept another penalty.

Russell also said his retirement in Malaysia and the setback over the previous two race weekends had compromised his momentum. The Malaysian retirement, combined with team-mate Kimi Antonelli finishing second behind Red Bull's Max Verstappen, extended Antonelli's lead in the drivers' championship to 84 points.

Mercedes is changing the cars' specifications for Singapore as it assesses an aerodynamic upgrade introduced in Malaysia last weekend. The upgrade did not deliver the expected performance improvement, so the team is splitting the configurations to determine whether the result reflected characteristics of the Sepang track or a problem with the upgrade itself.

Russell will use the specification he drove to victory in Azerbaijan the week before Malaysia, while Antonelli will run the newer version. Russell said he had asked about the change on Friday in Sepang and noted the older configuration was not an early-season car.

“I actually asked a question already on Friday in Sepang. At the end of the day it's the car I'm reverting to is a car that was on pole by 0.8secs and Kimi won the race before, so it's important to remember the context. It's not like reverting back to a launch car.”

Russell said the car change made sense given his grid penalty and the low likelihood of a podium finish in Singapore. He said the priority was to find out whether the Malaysia result was a one-off or indicated a problem with the upgrade.

“Given the circumstances of the grid penalty as well, it just seemed like a no-brainer. For me, unfortunately we're not going to be fighting for a podium this weekend, it's exceptionally unlikely, so it's more important for us to try and understand, was Malaysia a one-off or was it the upgrade?”

Antonelli is also likely to face a back-of-the-grid penalty when Mercedes introduces the upgraded engine. He previously started from 19th at the Italian Grand Prix and won the race.

Russell said reliability problems have affected both Mercedes drivers this season, and that he has experienced more failures this year than in his previous three seasons combined. He also said his own performance had not been strong enough, but that setbacks had affected momentum.

“I've probably had more failures this year than I've had in the three seasons put together, and of course it's tough to take,” he said. “If I'm being 100% fair with myself, as I've said before, the performance this season hasn't been strong enough, and it probably would have affected me more if I'd have still been in the fight.”

He added: “But obviously the pressure and the momentum, every setback has an impact on that momentum.” Russell cited an engine failure in Canada, a drive-through penalty in Monaco, and performance losses involving the power unit at Silverstone and Spa. He said the loss in Malaysia had effectively compromised two weekends for him, and concluded: “it's been pretty incredible how things have panned out this year, but I think just focus on what you can control.”

The Singapore Grand Prix runs from Oct. 9 to 11. BBC Radio 5 Sports Extra will carry live commentary, with live text updates on the BBC Sport website and app.