Lewis Hamilton was unable to match Valtteri Bottas as the world champion's Mercedes team-mate completed a practice double for the Russian Grand Prix.
Hamilton's attempt at matching Michael Schumacher's victory record began by finishing a surprise last but one in the opening running.
And although the six-time world champion moved up the order later in the day, it is Bottas who holds the advantage heading into the weekend.
Hamilton trailed the Finn by 0.2 seconds at the Sochi Autodrom, with Daniel Ricciardo a distant third for Renault and the McLaren duo of Carlos Sainz and Lando Norris fourth and fifth respectively. Ricciardo was more than a second off Bottas' pace with Mercedes the class of the field once more.
Hamilton moved to within one victory of Schumacher's 91 wins following his triumph in Mugello earlier this month. The Brit was on course to finish ahead of Bottas on Friday afternoon, but ran wide at Turn 13 and abandoned his lap.
Hamilton was among a number of drivers to slip off the circuit during both practice sessions, with Max Verstappen on a personal-best lap before he spun in his Red Bull. The Dutchman had to settle for seventh.
The most significant accident involved Nicholas Latifi earlier on Friday. The rookie driver lost control of his Williams through the right-handed Turn 10 at the Sochi Autodrom, sliding backwards into the barriers.
Latifi sustained significant damage to his car but emerged unscathed from the heavy impact before the session was suspended to recover his stricken car. His Williams team performed an impressive repair job to ensure the Canadian could take part in the second session.
He finished 15th, one spot ahead of George Russell in the other Williams.
McLaren's Carlos Sainz spun at the same corner as Latifi, but the Spaniard was able to limp back to the pits, albeit without his broken rear wing.
Hamilton's chance of a fast lap in the morning running was thwarted when he was caught out under braking for the opening corner. Hamilton missed the apex of the right-handed bend before heading through the run-off area and cancelling his lap.
For team-mate Bottas, who trails Hamilton in the championship standings by 55 points, there were no such concerns. The Finn is chasing his first win since the opening round of the campaign in Austria.
Elsewhere, Charles Leclerc and Sebastian Vettel finished eighth and tenth on an improved, yet unremarkable, showing for Ferrari.
The 10th round of the season is being played out in front of a significant number of spectators for the first time this season, with 30,000 fans expected through the gates.
