Russell takes blame for costly Verstappen collision in Las Vegas
Russell was handed a five-second penalty for a lap 25 clash with Red Bull's triple world champion and eventual winner Max Verstappen that demoted the Briton from fourth at the finish to eighth.
Ferrari ended up scoring 16 points more than Mercedes and closed the gap to four with just one race remaining in Abu Dhabi next weekend.
"Just another massively missed opportunity this weekend," Russell told Sky Sports television.
"The incident with Max was totally my fault. I didn't see him, he was totally in my blind spot going around turn 11. I wasn't really expecting to be overtaken there because you've got the big long straight with DRS afterwards.
"We were on course for an easy podium, it was pretty straightforward.
"This season is sort of one thing after another."
Mercedes team boss Toto Wolff said it was game over once Russell incurred the penalty but remained optimistic for the finale.
"I think we hopefully can recover and score solid podiums," he said of Abu Dhabi.
Ferrari boss Fred Vasseur was also hopeful of a strong finish to the season after Charles Leclerc started on pole position and finished second with Carlos Sainz
sixth.
"We must keep the momentum going into Abu Dhabi, both drivers are doing a fantastic job and I believe we can catch Mercedes," he said.
"We won in Singapore when Red Bull was off the pace but this time we were fighting them right up to the final corner."