Nico Hulkenberg insists Haas must "get a grip" over its upgrades after its United States Grand Prix package failed to deliver what the team hoped.
A complete reworking of the VF-23 broke cover in Austin, but the team has suffered two poor races in both the US and Mexico City, including team-mate Kevin Magnussen crashing out heavily in the latter with a suspension failure.
Hulkenberg lashed out at the team following the Mexico weekend, saying it could simply not compete if it did not sort its problems - with the team now sitting last in the Constructors' following AlphaTauri's upturn in performance.
The German now insisted the team needs to focus and get a read on its lack of performance.
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Hulkenberg wants a grip on Haas
"Obviously in Austin, we had the Sprint weekend, which was difficult," Hulkenberg explained to media including RacingNews365.
"Mexico is always very specific and special with the altitude, but I think we've seen that the upgrade is not a big step up in performance and we're not suddenly in the points-scoring positions.
"It might have given us some clues and directions for the future, but we still needed some instant performance right here, right now and that just didn't happen.
"It is still TBC [if the team have got a better handle on the upgrade], so now we have to demonstrate - the factory guys, the designers and the aero guys that they understand, get a grip on this and [deliver] a more competitive package."