Toyota is adamant that it will finally face a challenge from the LMP1 privateers at next month's Shanghai round of the World Endurance Championship.
The Japanese manufacturer believes that the new system of success handicaps introduced for the LMP1 class this season will make it difficult for its TS050 HYBRID to maintain a run of WEC victories dating back to August 2018.
The Toyotas will be further slowed in comparison to their privateer rivals, Rebellion Racing and the Team LNT Ginetta squad, at the Chinese event on November 10 after finishing one-two in last Sunday's Fuji round of the 2019/20 WEC.
Toyota Motorsport GmbH technical director Pascal Vasselon told Autosport: "Shanghai will be very difficult for us because we will get another step of success handicaps.
"In Shanghai, Rebellion should be strong challengers for pole and in the race as well."
Sebastien Buemi, who took victory at Toyota's home track last weekend with Kazuki Nakajima and Brendon Hartley, echoed Vasselon's view.
"Sooner or later Rebellion and maybe Ginetta will be quicker than us," he said.
"We will go to Shanghai another step slower with the penalties, and at some point, if they don't make any mistakes, they are going to beat us.
"I think that could be in Shanghai."
Vasselon explained after the Fuji race that the reduction in the fuel allowed to the TS050 and hybrid energy that it can deploy is now making it hard for the Toyota drivers to overtake LMP2 machinery on the straights.
"We are at a level with the powertrain that is close to critical," he said.
"Today we managed to pass the LMP2s, but just."
The two Toyota will be equally penalised at Shanghai after each notching up a win, a second place and a pole position in the two WEC rounds so far this season.
The penalties for each LMP1 are based on the gap in championship points to the lowest-placed car in the classification.
Cars are penalised by a given amount of time per point, up to a maximum of 40, multiplied by the length of the track in kilometres.
The penalties for Shanghai have yet to be published, but the Toyotas should be penalised by 2.5s per lap.
The #1 Rebellion-Gibson R-13, which finished third at Fuji in the hands of Bruno Senna, Norman Nato and Gustavo Menezes, should get one second's worth of handicaps.
The exact amounts will depend on the co-efficient used to make the calculations.
It was initially announced as 0.008s per point, but was increased to 0.012s after the gap between Toyota and the privateers proved bigger than expected at the Silverstone season opener in September.
Toyota's prediction that Rebellion would be in a position to fight with its cars at Fuji proved to be incorrect.
Vasselon expressed surprise at the lack of pace of the solo R-13, but the team explained that it was hamstrung by the warmer than usual temperatures at Fuji over the weekend.
The two tyre choices Michelin brought to Japan were a soft compound and Rebellion reckoned it would have been more competitive had the medium compound been available.
The was borne out by the pace of the R-13 in the final stages of the race as the temperatures dropped when Menezes matched the Toyotas.
Beaten Toyota drivers say handicap impossible to overcome
By Jamie Klein
The drivers of the second-placed Toyota felt they were powerless to overcome their handicap against the winning sister entry.
Kobayashi and his team-mates in the #7 TS050, Jose Maria Lopez and Mike Conway, ended up 33.9s down on the race-winning #8 Toyota at Fuji, hobbled by their theoretical handicap of 0.4s a lap after their Silverstone triumph.
The gap between the Toyotas had been as large as 50s before the #8 car picked up a drive-through penalty for pitlane speeding.
Kobayashi admitted after opening practice on Friday that he felt "demotivated" because he knew he had no chance of winning, but after the race said he was satisfied to have finished closer to the #8 car than team simulations had forecast.
"The calculations said in theory [we would be] 90 seconds slower than car #8. We finished 33 seconds [behind], so we did a good job," he told Autosport.
"Unfortunately this is the handicap in the end.
"In future we know as soon as we have a gap in the points [between the cars], if we do a mistake in the race or we are not scoring points, the next couple of races we'll be very quick.
"We'll know the result [beforehand]."
Asked if he felt the current system was bad for the fans, Kobayashi replied: "Yeah. It's hard for them to know how much [of the gap] actually is the handicap.
"The team calculates as much as possible but in the end the calculation was not accurate."
Lopez echoed Kobayashi's sentiments, and admitted that while "the motivation changes" as a result of the handicap system, he is looking forward to a fairer fight next month at Shanghai now both Toyotas are level on points - and will therefore have the same penalty.
"I think overall the performance was good, sometimes we were quicker than car #8," said Lopez.
"Considering the handicap, arriving 30s [behind] was a good result for us.
"When we put on the helmet we try to adapt and take the maximum out of the car. That's our job, no matter what the penalty is or the regulations. You have to try.
"Now we come back again in Shanghai, we'll be the same. If they are better in Shanghai we'll be better in the [following] race.
"The system is designed for that, you'll never be able to pull away in the points because another car will always be quicker.
"The important thing is to not have a DNF, keep scoring points, and get to Le Mans, which I think will be the race that will make the difference."