Renault conceded errors cost Fernando Alonso victory at the China Grand Prix - and top spot in the title race.
Alonso's victory hopes were undone by strategic errors
Alonso's huge lead evaporated following an incorrect tyre choice, and a bungled pit stop left him unable to recover.
"We are making no excuses," said Renault director of engineering Pat Symonds. "We should have won the race.
"Renault and its Michelin tyres were dominant in all conditions and the fact we did not win is intensely frustrating as Fernando drove brilliantly."
Renault's Michelin tyres appeared more suited to the changeable weather conditions in Shanghai than the Bridgestones used by rivals Ferrari.
Alonso had comfortably taken pole and streaked away from the field but the Spaniard lost the upper hand when he pitted for fuel and tyres on lap 22 and the team fitted a pair of new intermediate front tyres.
He immediately lost grip and saw his lead reeled in by team-mate Giancarlo Fisichella and Schumacher, who did not change their tyres until much later in the race.
The race showed us that the Renault is still the fastest car out there
Renault engineering director Pat Symonds
Alonso survived 13 laps before he came back to the pits to revert to slicks but a problem with a loose wheel nut saw him trapped in the pits for 18 seconds leaving him short on time to close down Schumacher.
"Fernando told us his front tyres were badly worn and we decided to change them but leave the rears on," said Symonds.
"It soon became clear that the track was drying quickly, and that the decision had been the wrong one.
"As a result, we took the risk of stopping very early to switch Fernando to dry tyres but a delay cost us more time.
"Fernando once again drove fantastically to close in on Michael, but we simply ran out of laps."
Renault are determined to learn from their mistakes and take the positives from Shanghai, where Alonso and Fisichella showed plenty of pace and Renault recovered a one-point advantage in the constructors' race.
Symonds said: "We go to the final two races with renewed confidence.
"The race showed us that the Renault is still the fastest car out there and we fully intend to make use of it in the final races and a thrilling title showdown."