Lewis Hamilton claims there is a 'massive gap' in speed between his Mercedes W15 car and his Red Bull rivals.
The Silver Arrows had a weekend to forget as both Hamilton and George Russell retired from the Australian Grand Prix in Melbourne.
Max Verstappen retired early in the race after a brake issue, with his car on fire as it entered the pit lane.
Seven-time world champion Hamilton was forced to retire a few laps later due to an engine problem.
Lewis Hamilton admits there is a massive gap between Mercedes and Red Bull
Sky Sports
Hamilton had criticised his car after qualifying on Saturday, claiming the inconsistency of it 'messes with the mind'.
He is in his 12th and final season at Mercedes having committed to joining Ferrari from 2025.
Explaining the problem suffered on Sunday, Hamilton told Sky Sports: "I think the engine ceased.
"It just appeared out of nowhere, it was a split-second thing."
Hamilton was attempting to overtake Red Bull's Sergio Perez before he retired but to no avail.
And he admits Mercedes are a long way behind the reigning world champions, adding: "Oh it's a massive gap.
"I think they have a second on us, something like that.
"He was on fresh tyres but the way he pulled away down the straight, I was like... Same as last year."
His team-mate Russell suffered a late retirement on the final race of the lap after crashing into the barriers and flipping on his side.
The Brit was trying to overtake Fernando Alonso in sixth and the pair were under investigation for the incident.
Some felt Alonso brake-tested Russell but the Mercedes star refused to accuse the Spaniard until seeing it again.
Russell said: "My take is I've gone off and that's on me.
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Lewis Hamilton retired early due to engine failure at the Australian Grand Prix
Getty
"I was half a second behind Fernando 100m before the corner then suddenly he came towards me extremely quick and I was right on his gearbox. I don't know if he had a problem or not.
"We're off to the stewards and that's a bit bizarre in a circumstance like this.
"I've got nothing more to say right now. I need to see everything, just disappointed to end the race like that.
"It's clear he braked 100m before the corner and was back on the throttle again and took the corner normally. We've already seen the data of that.
George Russell crashed out of the Australian Grand Prix on the final lap
Getty
"I'm not going to accuse him of anything until we see further.
"I was right behind him for many, many laps. I was half a second behind him before the corner
"Then, suddenly he slowed up dramatically and got back on the power. I wasn't expecting it and he caught me by surprise.
"That part is on me. It's interesting he's been called by the stewards. I'm intrigued as to what they have to say."