Romain Grosjean says the Haas Formula 1 team could still revert to its original spec car later in 2019 despite settling on a revised Belgian and Italian Grands Prix package.
After experimenting with running different configurations across its two cars in the races leading up to the summer break - a programme that included Grosjean going back to Haas's start-of-season package - Haas is using a 'refined', low-downforce, version of its most recent iteration for both drivers at Spa and Monza.
But Grosjean, who has always preferred the original version, said Haas had no choice as the Spa/Monza wings could not be used on the Melbourne spec car.
"It's not a decision, it was a no choice option because the low downforce package is not runnable on the old car," he said when asked about the change by Autosport.
"I knew for a long time, since before Silverstone, that we had to be running the new car here and Monza, and then we can decide for the next few races.
"So it doesn't mean that the old lady is not going to come back in the garage. Actually it's because we didn't have a choice, the wings don't fit on the old car."
Asked if he expected to see the original spec back after Monza he said: "Maybe. Singapore, let's see how that one behaves. Russia most likely."
Haas team principal Gunther Steiner insisted that the latest spec gave the team the best opportunity to address its problems for 2020.
"We think it's the best going forward, to understand better what not to do for next year," said Steiner.
"That decision we just reached before the break, we met up in Maranello with the aero people and came up with this solution, that this is the best going forward, so we can learn and try to cure our problem that we've got.
"This gives us the most stable platform to learn what to do for next year, put it like this."
Magnussen supported the decision to focus on the latest spec, which he has always stuck with.
"It's been tricky, it's shown some weaknesses, but also it's shown some big strengths," he said.
"So we'll try and pursue that a little bit and invest in the future development while doing what's best right now.
"It's better to work with this package right now and try and make it work than step back and lose ground like that."
Asked by Autosport to elaborate on the latest spec's strengths he said: "The car is very nice to drive when it works, but then it can turn on its head and be a dog to drive as well.
"So when it's good it's really good. So that's what we want to try and pursue."