The team confirmed on Tuesday that the Briton had no engines left in his season's allocation of four and would have to take a new one for the sprint weekend, with the corresponding penalties likely sending him to the back row for Sunday's race.
Russell retired from the Bahrain Grand Prix in Malaysia last weekend with a power unit problem five laps from the finish while he was in third place. Mercedes deputy principal Bradley Lord said investigations into Russell's Sepang engine failure remained ongoing but it was clearly something mechanical.
The pre-season title favourite remained second overall but is now a considerable 84 points behind championship-leading teammate Kimi Antonelli.
Saturday is the last sprint of the season - with engine penalties not applying for that 100km race - and there are six rounds scheduled after Singapore, meaning 20-year-old Antonelli is on track to clinch the title as Formula 1's youngest champion with several races to spare.
Russell and Mercedes had always known he would need a new engine, with a penalty, but had hoped to take it at the US Grand Prix in Austin - the race after Singapore - when the team had also planned to introduce an engine upgrade that could now be brought forward.
That Texan circuit, unlike tight and slow Singapore, generally sees plenty of overtaking. At the Asian street circuit, it will be much more difficult for the Brit ti fight his way through the field.
The lowest winning grid position at the Marina Bay track is 15th for Spaniard Fernando Alonso in a now-notorious 2008 race in which his Brazilian teammate Nelson Piquet crashed his Renault deliberately on team orders. Of the 16 races held there to date, 11 have been won from pole.
Antonelli took his engine penalty at Monza, his home race, and won it from 19th place on the grid.