Force India F1 boss calls Valtteri Bottas star of the season

Bottas scored three consecutive podium finishes in the Austrian, British and German Grands Prix and lies fifth in the world championship, 55 points clear of new Williams team-mate Felipe Massa after 11 races.

Mallya, who plans to retain his current drivers Nico Hulkenberg and Sergio Perez for next season, reckons Bottas has "shocked everybody" with his consistently strong showings for the much-improved Williams team.

"There can be no two opinions that Bottas has been the star of the season so far," Mallya told AUTOSPORT.

"Here you have the great Massa, and here you have a guy who's come out of GP3, and the first thing that comes to your mind is that he's going to be half a second behind.

"He's shocked everybody and is doing a fantastic job under pressure.

"Not only does he have the killer instinct but also the maturity not to get flustered."

Mallya also reserved praise for Daniel Ricciardo, who has out-performed his four-time world champion team-mate Sebastian Vettel and won two races since stepping up from Toro Rosso to Red Bull this year.

"Daniel Ricciardo [has also been] very impressive," he added.

"I think even Red Bull are wondering what's going on."