Manor driver Pascal Wehrlein admitted he was disappointed with his result at the Russian Grand Prix after a battle with rivals from Sauber accelerated tyre wear on the MRT05.
Wehrlein scrapped with Felipe Nasr on several occasions but had to pit for a second time, dropping him to the back of the pack.
Wehrlein's situation was exacerbated by a problem with the left rear tyre in the pits, costing the youngster 20 seconds, as he trailed home in 18th place.
"A disappointing result," he said. "I got a good start and managed to avoid all the problems in the first couple of corners, then the first stint was quite good for me.
"I had a good fight with the Saubers but after the first pit stop they were in front of me. I tried to push hard to overtake one of them again but I couldn’t manage it and I destroyed my tyres behind them so I had to box again.
"At the second stop we had a problem with the left-rear which lost us a lot of time but by then I think 18th was the best we could hope for.
"Now we have to focus on heading to Europe and what we can do to improve. My thanks to the team so far for a good first few races and their hard work."