Seven-time world champion Lewis Hamilton said Mercedes are in "no-man's land" after he finished Sunday's Emilia-Romagna Grand Prix in sixth place and 35 seconds behind Red Bull's race winner Max Verstappen.
Teammate George Russell finished seventh and Mercedes have fallen further behind in the Formula One constructors' standings -- fourth overall at 79 points while third-place McLaren, who also use Mercedes engines, have 154.
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"We are in no-man's land. There wasn't much more for us to get today," Hamilton said.
"It is where we are and we have to do the best we can and that is the best we could do today."
Hamilton will move to Ferrari at the end of the season and was racing in Italy for the first time since that was announced.
Russell also referred to "no-man's land," but said the once-dominant team was still "super-motivated."
"We have got to just keep pushing. The car was capable of P6 and P7 and that is where we finished."
Team boss Toto Wolff said Mercedes has taken a small step forward.
"Our closest competitors have also done so recently, but we have closed the gap to the front a little. We still have a lot of work to do and, of course, we are all frustrated finishing P6 and P7," Wolff said.
"There is more to come though, and it is all about making incremental gains."