Toto Wolff has revealed the disappointment at losing last year's F1 drivers' title still runs "very deep" inside Lewis Hamilton.
Since the acrimony that surrounded the final race of last season, Hamilton has so far stayed silent, fuelling rumours as to whether he will decide to retire ahead of the new campaign.
According to Wolff, the disillusionment felt at the time at the way the end of the grand prix in Abu Dhabi was handled by FIA race director Michael Masi remains.
With an FIA inquiry ongoing and no details due until early February as to what plans are likely to be in place for this season, and whether Masi will continue in his role, it is likely doubts around Hamilton will continue for at least another couple of weeks.
Asked in an interview with Auto Motor und Sport as to how deep the disappointment runs after losing out on the drivers' title, Wolff said: "It's very deep. Lewis, I and the whole team are disillusioned.
"We love this sport because it's honest. The stopwatch never lies. But if we break the fundamental principle of fairness and the stopwatch is no longer relevant, then you doubt this sport, that all your work, blood, sweat and tears can be taken away from you.
"It's going to take a long time to digest. I don't think we'll ever get over that, especially Lewis as a driver. At least we can try together with the FIA to do better in the future."
Wolff is now expecting the FIA to come up with a positive plan of action, the results of which will not be fully ratified until a World Motor Sport Council meeting on March 18, two days before the first grand prix of a record-breaking 23-race season in Bahrain.
"I expect actions and not just words," insisted Wolff. "In a sport that's supposed to be a sport, we can't freestyle like that with the set of rules.
"Before the start of the new season, there must be clarity about the rules so that every driver, team and fan knows what is allowed and what is not.
"In the end, we provide entertainment, but no decision should break the rules for the sake of the show."
If Hamilton does return, Wolff is fully expecting him to display the qualities of a seven-time champion and take the fight to whichever driver will prove to be his main rival.
"The capacity of Lewis is often wrongly questioned," remarked Wolff.
"Even after the events in Abu Dhabi, he immediately congratulated Max. Lewis only wants one thing - fair competition on the track. We will deliver that."