Romain Grosjean has blamed "adrenaline" on his post-race rants about rival Marcus Ericsson following the Chinese grand prix.

Swede Ericsson, who drives for Sauber, blasted the "unprofessional" Frenchman Grosjean, who had called Ericsson names following a collision in Shanghai.

"He said that I was an idiot, I'm blind -- (Grosjean was) not behaving like a mature adult," Ericsson said.

Grosjean admits he was simply frustrated in China, where he struggled all weekend after two consecutive points finishes in Australia and Bahrain as Haas made its F1 debut.

"We had two superb first grands prix and were then unsuccessful in China," he told RMC. "But it is almost positive because it allows us to analyse, to understand and to realise that F1 is not as easy as it seems.

"Under the influence of adrenaline, I called Ericsson a fool because I was high in the drivers' championship and wanted to continue my momentum.

"In the past, I have had some incidents and I learned from the experience and the feedback that I received," Grosjean added.

He said he has no doubt Haas will bounce back stronger in Russia, but former F1 driver and fellow Frenchman Franck Montagny is not so sure.

"Grosjean was clearly not at the party in China," he told Le Point, "which after two superb performances is incomprehensible.

"It may be a problem of the pressure being too high, but that does not explain everything," Montagny added.

(GMM)