Lewis Hamilton says he is "incredibly disappointed" with his Russian Grand Prix qualifying errors, and has apologised to his Mercedes team.
Hamilton and Mercedes topped Q1 and Q2 at the Sochi Autodrom on Intermediate tyres, but their session unravelled in Q3 amid the switch to slicks.
Hamilton initially made a mistake on his return to the pit lane, clipping the pit wall and losing time as mechanics replaced his front wing, before he spun out on his only lap with the Soft compound tyre.
He ended up fourth, behind star performers Lando Norris, Carlos Sainz and George Russell, and expressed frustration with his own performance.
"It was just a mistake from myself. Ultimately, I'm incredibly disappointed in myself," Hamilton told Sky Sports after qualifying.
"Up until then, I was in the groove, I was really in the zone.
"I'm really sorry for all the team that are here, and back at the factory, because obviously that's not what you expect from a champion.
"It is what it is, and I'll do my best tomorrow to try and rectify it."
Hamilton described conditions as "horrible" in the closing stages of Q3.
He summed up: "At the end, [we had] very poor grip, [it's] very slippery when you don't have any temperature, you know, and I was losing temperature during the lap. Even twice in the wall... that's very rare for me."
Hamilton trails Max Verstappen by five points in the standings ahead of Sunday's race, though Verstappen will start from the back of the grid after taking on his fourth power unit of the season.
Video: The secrets of the Sochi Autodrom circuit
Follow Rudy van Buren as he takes you on a flying lap around the Sochi Autodrom in Russia.