Toyota has been accused of "playing games" with the true pace of its TS050 HYBRIDs during last weekend's World Endurance Championship opener at Silverstone by Rebellion's Gustavo Menezes.
Menezes made the comments after Toyota claimed a dominant one-two finish at Silverstone, finishing a lap clear of the #3 Rebellion R-13 shared by Loic Duval, Pipo Derani and Nathanael Berthon - while Menezes's #1 Rebellion that he shares with Norman Nato and Bruno Senna finished 10th and fifth in class.
Toyota technical director Pascal Vasselon declared after qualifying that Rebellion had demonstrated enough speed to threaten the TS050 HYBRIDs in the race.
But Menezes says the race proved Toyota had not revealed its true pace.
"It was very clear they still have more pace than us," Menezes told Autosport. "We have to continue to work on our own pace and our problems, to eliminate those, but we also could see that Toyota was further ahead than they looked all weekend by a large margin.
"Considering their race pace in practice was in the [1m]39s and [in the race] they ran low [1m]37s, it's pretty clear they had more in the tank. And they are very good at playing those games.
"But the system does catch up, and I think we'll see it come into play later in the championship."
The WEC has introduced success handicaps for the 2019/20 season and Toyota will be pegged back after dominating at Silverstone.
When asked if he believed if Rebellion could challenge Toyota at Fuji with the help of success handicaps, Menezes replied: "In my personal opinion, it will take another race.
"Japan is Toyota's home race, and they're going to do everything they can to win that. Also, I think Fuji suits their car more than ours, our car definitely does well in high-speed corners and not so much in low-speed acceleration zones, so I think they'll have us there.
"I'm more optimistic for Shanghai, but it doesn't mean we won't give it everything at Fuji."
Drivers from both of the Toyota crews expressed surprise that Rebellion did not put up a better fight in the race.
Brendon Hartley, who finished second alongside Kazuki Nakajima and Sebastien Buemi in the #8 Toyota, told Autosport: "Definitely the gap at the end of the race was a surprise, but it's not completely fair because of the penalties, maybe a few mistakes.
"In free practice, they looked a lot closer, so I don't know if they were a bit hard on the tyres. But I think they didn't get everything together today."
Mike Conway, who was one of the drivers in the winning #7 Toyota said: "Maybe the track came more towards us than it did to them [Rebellion], I don't know.
"We were strong in the beginning, lap times were a bit more than I thought, and our averages were very good.
"Once we get [the EoT] more on their side, it will be an even better fight. I hope it's a bit closer [in Fuji] than it was today."