Force India's Bob Fernley believes McLaren and the works Renault team will both be huge forces to be reckoned with in this year's campaign.
Thanks to its remarkable level of performance and consistency, the Silverstone-based outfit has finished 'best of the rest' in the Constructors' standings in the last two seasons.
But Fernley is expecting Force India to be challenged in 2018 by its two rivals which enjoy bigger budgets and the potential to raise their level of performance.
"Caution would be both Renault and McLaren look quite handy so make sure we focus on the winter," Fernley told Motorsport.com.
"They are a significant threat and we need to take it seriously. We need to do quite a bit of work ourselves to make sure that we accommodate that.
"There will be no quarter given for those three cars. The three teams will be locked into a massive battle."
Force India has shown a remarkable ability to make the most of one of the smallest budgets on the grid. At £90m, the pink outfit's funding significantly dwarfs that of McLaren (£185M) and Renault (£150M).
"It'll always be difficult to compete against the bigger budgets, but saying that, we've done it for two years in a row so there's no reason why we can't do it for a third," said Fernley.