Yuki Tsunoda conceded to being “quite confused” over his performance deficit to AlphaTauri team-mate Pierre Gasly at the Russian Grand Prix.
Gasly finished second practice at the Sochi Autodrom in third spot, behind only the Mercedes drivers, but Tsunoda languished down in 18th spot.
Tsunoda’s best time was over two seconds down on Gasly’s personal best effort.
“The balance is not too bad, just the general grip… or something like, I don’t know, we have to figure out the difference between my team-mate [and me],” he said.
“My team-mate is doing a really good job, he’s P3, top five, and on the other side I’m in P18 or something like that.
“Yeah, I mean, just have to look more deeply what’s the issues there. Yeah, currently, I’m quite confused.”
Gasly expressed confidence over his pace but is wary of the potential of main rivals Alpine.
“I think we had a fantastic day with the sixth [best] time this morning and third time this afternoon,” said Gasly.
“In terms of performance, it seems to work well, so I’m really happy about it.
“Inside the car it is still not easy, not feeling 100% comfortable with the balance and [there’s] quite a few things to improve.
“We know Charles [Leclerc] is taking a penalty as well [as Max Verstappen], so there’s going to be some opportunities.
“At the moment we’re focusing on our package and the main focus for us is the two Alpines, they are fast as well, we saw Fernando [Alonso] and Esteban [Ocon] put in some fast laps, so I expect a tight battle with them as it’s important for us to start catching them in the championship.”