Valtteri Bottas forecast he and Mercedes team-mate Lewis Hamilton would be faster and more competitive on Saturday after they dominated Friday practice at the Russian Grand Prix.
The Finn topped the times by two-tenths ahead of Hamilton as the two 'black arrow' men wound up more than a second clear of their nearest rivals.
"It was a messy day with a lot of interruptions," said Bottas.
"Lots of red flags and quite limited running, so I am sure we have a lot more to come," he added.
Hamilton, who leads Bottas by 55 points in the title race and is within one race of equalling Michael Schumacher's record 91 Grand Prix wins, agreed with his team-mate.
"I don't feel like I was particularly quick," said the six-time champion.
"It didn't start off very good. Practice 1 was pretty poor, I had a lock-up at Turn One on the soft tyre, then went out on the hard tyre and completely destroyed the tyres. So P1 was scrap.
"In P2, it was a lot better, but it is still a work in progress. There are things I need to improve on in my driving and then in the set-up. It's one step at a time. I've got a lot of work to do, but that's nothing new.
The two Mercedes men were more than a second clear of third-placed Daniel Ricciardo of Renault despite enduring a difficult day of off-track excursions on the slippery track.
It was the sixth Friday in a row that had seen Bottas topping the times – and at a track where he claimed his maiden win in 2017 and where Mercedes are unbeaten, having won all six events since the inaugural race in 2014. Hamilton has won four times and former team-mate Nico Rosberg won in 2016 on his way to claiming the title.
In front of a meagre scattering of fans to witness practice, with 30,000 due to attend Sunday's race, Carlos Sainz was fourth ahead of his McLaren team-mate Lando Norris and Sergio Perez of Racing Point.
The Russian race will be the first major sports event to be run in front of a significant crowd in the Covid-19 era.
Max Verstappen was down in seventh for Red Bull ahead of Charles Leclerc in the leading Ferrari, Esteban Ocon of Renault and four-time champion Sebastian Vettel in the second Ferrari.